# Low Pressure warning - Car wont start



## red23 (Jan 24, 2015)

HI All,

I honesty cannot believe this but i have a new problem with the car [smiley=bigcry.gif]

I went to start the car today and got a "low pressure warning" symbol in the car and it won't start up. You can hear the car trying to turn over but wont.

There is plenty oil in the car as was serviced 2 months ago.

This issue has come immediately after i just fixed a battery issue - turned out that the new battery had reverse polarity so was sending power the wrong way round.

Car ran perfectly before this but has been sitting on the drive for 1 week since the battery issues started.

Please if anyone can help im pretty desperate, this car is destroying my will to live :x


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## Hoggy (May 8, 2002)

Hi, Do you mean the engine won't crank over or it will but won't start?
Hoggy.


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## red23 (Jan 24, 2015)

Hoggy said:


> Hi, Do you mean the engine won't crank over or it will but won't start?
> Hoggy.


Hi there,

I mean it cranks over and tries to start but struggles.


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## Hoggy (May 8, 2002)

red23 said:


> Hoggy said:
> 
> 
> > Hi, Do you mean the engine won't crank over or it will but won't start?
> ...


Hi, Probably a knackered battery after the abuse it's had, measure the battery volts or jump it with another battery.
Hoggy


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## red23 (Jan 24, 2015)

Hoggy said:


> red23 said:
> 
> 
> > Hoggy said:
> ...


Measured the battery and its seems fully charged.

The quesiton is why would it be showing up an oil pressure warning lamp, it's never done this before?


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## Hoggy (May 8, 2002)

red23 said:


> Why would it be showing up an oil pressure warning lamp, it's never done this before.


Hi, I expect the reverse polarity has upset the electronics. Disconnect the battery for 10 minutes, turn Ign ON for a few minutes, turn Ign OFF, reconnect battery & try again. What were the battery volts? 
Hoggy.


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## red23 (Jan 24, 2015)

Hoggy said:


> red23 said:
> 
> 
> > Why would it be showing up an oil pressure warning lamp, it's never done this before.
> ...


Hopefully mate, i'll give that a go.

The battery volts are 13.11 volts

Connected ODB-11 shows no warnings.


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## Hoggy (May 8, 2002)

red23 said:


> . The battery volts are 13.11 volts


Hi, A battery will never be 13.11 unless it's connected to a charger or engine is running. 
Low oil pressure won't prevent the engine running (not initially anyway) but is the oil level O.K.
Hoggy.


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## FNChaos (Nov 30, 2016)

red23 said:


> Measured the battery and its seems fully charged.
> 
> The quesiton is why would it be showing up an oil pressure warning lamp, it's never done this before?


How exactly did you measure your battery? A simple voltage measurement tells you nothing about the current capacity.
Hell, I can connect 8 AAA penlight batteries in series and get 12 volts but you can't start a car with it.

Reversing your battery polarity is bad, like extremely bad. [smiley=skull.gif] 
Hopefully all of your various modules have diode protection? otherwise you could have a very expensive repair ahead.


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## red23 (Jan 24, 2015)

FNChaos said:


> red23 said:
> 
> 
> > Measured the battery and its seems fully charged.
> ...


The test was simply done with a multimeter.

The battery with the reversed polarity was brand new from eurocar parts.

How could i tell if there is diode protection. I'm getting pretty worried now. Everything else appears to work apart from the car starting, all electrics appear "ok".


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## C00P5TT5 (Jul 10, 2016)

Do what hoggy suggested, worked for me.

You will get a load of warning lights, but drive it and they will clear


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## Hoggy (May 8, 2002)

red23 said:


> The test was simply done with a multimeter.
> 
> The battery with the reversed polarity was brand new from eurocar parts.
> 
> How could i tell if there is diode protection. I'm getting pretty worried now. Everything else appears to work apart from the car starting, all electrics appear "ok".


Hi, You can't tell, only if you end up with a big bill will you know the electronics are knackered.
Your multimeter must be on the wrong scale as it will never be 13.11 volts.
Try what I suggested, hopefully, you may be lucky, otherwise leave battery on charge for 12 hours minimum.
Hoggy.


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## red23 (Jan 24, 2015)

C00P5TT5 said:


> Do what hoggy suggested, worked for me.
> 
> You will get a load of warning lights, but drive it and they will clear


Great will give this a go when its light outside. Was this also caused by reverse polarity in a battery?


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## FNChaos (Nov 30, 2016)

Typically battery cables are short enough that it is hard to cross them and make a mistake, however batteries can come with the positive on either side to fit different engine bay layouts. If your positive terminal is opposite of where it should be then you purchased the wrong battery.

It is a good thing you didn't try jump-starting your car with the battery reversed, as you would have created one hella arc welder and / or an acid-spewing explosion.

Fingers crossed that Audi engineered 'idiot-proof'(sorry) protection into their design? If not, your repair costs likely will exceed to value of your car. Fortunately the fact that other systems appear to work is a good sign. Guessing you dumped / corrupted your ECU 's memory. 'Maybe' the imobilizer needs to be reprogrammed?


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## Hoggy (May 8, 2002)

Hi, Reversing the polarity is one of the worst things to do., especially if you turned the Ign ON & tried to start.
Hoggy.


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## IPG3.6 (Sep 5, 2015)

The low oil warning is just one of the anomalies that show up after the first crank isn't successful - along with many other lights commonly known as "christmas tree" dash. lol

Hope you get it sorted soon!


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## red23 (Jan 24, 2015)

Hi all

So I did as hoggy said. Disconnected both positive and neg terminals and waited 10 mins. Tried ignition and left on (obviously dead with no power)

Connected back again and the results as below video


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## IPG3.6 (Sep 5, 2015)

Have you had a scan?

Posting up the full auto-scan result would be of greatest help here.


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## FNChaos (Nov 30, 2016)

Start checking all fuses and fusible links. These would be your first line of protection after reversing your battery.
There still might be more damage, but you won't know until you've verified / replaced any blown fuses.


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## Hoggy (May 8, 2002)

Hi, Is the battery fully charged, because it's turning over quite slowly, the rev meter is hardly moving?
Hoggy.


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## red23 (Jan 24, 2015)

Oops, posted this in wrong topic.

Not been able to check fuses yet as was dark when got home from work. Will do this in next couple of days when im back from travel.

Results as below:

Monday,09,March,2020,19:58:03:06555
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 19.6.2.2 (x64) HEX-V2 CB: 0.4508.4
Data version: 20200210 DS308.0
http://www.Ross-Tech.com

VIN: TRUZZZ8J881024122 License Plate:

Chassis Type: 8J (1K0)
Scan: 01 03 08 09 15 16 17 19 25 26 42 44 46 47 52 56 76

VIN: TRUZZZ8J881024122 Mileage: 73520km-45683miles

01-Engine -- Status: Malfunction 0010
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: Malfunction 0010
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: Malfunction 0010
19-CAN Gateway -- Status: Malfunction 0010
25-Immobilizer -- Status: OK 0000
26-Auto Roof -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: Cannot be reached 1100
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
56-Radio -- Status: OK 0000
76-Park Assist -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine Labels:. 06F-907-115-AXX.clb
Part No SW: 8J0 907 115 N HW: 8J0 907 115
Component: 2.0l R4/4V TFSI 0010
Revision: 5BH16--- Serial number: AUX7Z0G8FNE0MX
Coding: 0113000318070060
Shop #: WSC 01236 785 00200
VCID: 372B2B01134C1D0F38F-8062

1 Fault Found:
005634 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 0 km
Time Indication: 0

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: -40.0°C
Temperature: -40.0°C
Absolute Pres.: 0.0 mbar
Voltage: 0.000 V

Readiness: 0110 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8J0-614-517.clb
Part No SW: 8J0 614 517 HW: 8J0 614 517
Component: ESP MK60E1 0130
Revision: 00H51001
Coding: 0017424
Shop #: WSC 01236 785 00200
VCID: 6A8DC275107E70E7771-803E

1 Fault Found:
01826 - Sensor for Steering Angle (G85); Supply Voltage Terminal 30
000 - -
Freeze Frame:
Fault Status: 01100000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 173
Mileage: 73528 km
Time Indication: 0
Date: 2020.03.01
Time: 00:48:54

Freeze Frame:
Count: 128
Count: 12549
Count: 297
Count: 45056

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: None
Part No SW: 8J0 820 043 AF HW: 8J0 820 043 AF
Component: J255 Klima 1 Zone 0080
Revision: 00H07004 Serial number: 00000001061664
Coding: 1574148
Shop #: WSC 01236 785 00200
VCID: 6A8DC275107E70E7771-803E

1 Fault Found:
01206 - Signal for Duration of Ignition Off Time
008 - Implausible Signal
Freeze Frame:
Fault Status: 01101000
Fault Priority: 7
Fault Frequency: 1
Reset counter: 173
Mileage: 73528 km
Time Indication: 0
Date: 2020.03.01
Time: 00:48:57

-------------------------------------------------------------------------------
Address 09: Cent. Elect. Labels:. 8P0-907-279-30-H.lbl
Part No SW: 8P0 907 279 K HW: 8P0 907 279 K
Component: Bordnetz-SG H54 2501
Revision: 00H54000 Serial number: 00000007652457
Coding: E1041E8280141C00471800001800000000085E075C210802000000000000
Shop #: WSC 01236 785 00200
VCID: 45D751C959A07F9FBA3-8010

Subsystem 1 - Part No: 8J2 955 119 Labels: 1KX-955-119.CLB
Component: Wischer AU354 H08 0060
Coding: 00064784
Shop #: WSC 01236

Subsystem 2 - Part No: 4E0 910 557 B Labels: 8K0-955-559.CLB
Component: REGENLICHTSENSORH13 0100
Coding: 00149804
Shop #: WSC 01236

2 Faults Found:
01259 - Fuel Pump Relay (J17)
009 - Open or Short to Ground
Freeze Frame:
Fault Status: 01101001
Fault Priority: 5
Fault Frequency: 1
Reset counter: 173
Mileage: 73528 km
Time Indication: 0
Date: 2020.03.01
Time: 00:48:00

Freeze Frame:
ON
Voltage: 12.30 V
OFF
ON
OFF
OFF
OFF

01309 - Power Steering Control Module (J500)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 173
Mileage: 73528 km
Time Indication: 0
Date: 2020.03.01
Time: 00:48:00

Freeze Frame:
ON
Voltage: 12.30 V
OFF
ON
OFF
OFF
OFF

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8J0-959-655.lbl
Part No SW: 8J0 959 655 HW: 8J0 959 655
Component: -t Airbag 9.43 H02 0020
Revision: 93H02002 Serial number: 0036K001Y2AX
Coding: 0011636
Shop #: WSC 01236 785 00200
VCID: 79AFED3965D8CB7F8EB-802C

Subsystem 1 - Serial number: 6332DRB405C9892E%

Subsystem 2 - Serial number: 6342DRB405D54C09W

Subsystem 3 - Serial number: 63747RB402E9BDDCE

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 8P0-953-549-F.lbl
Part No SW: 8P0 953 549 F HW: 8P0 953 549 F
Component: J0527 H36 0070
Coding: 0002011
Shop #: WSC 01236 785 00200
VCID: 41DF45D94D8853BF86B-8014

Subsystem 1 - Part No: XXXXXXXXXXX
Component: E0221 H06 0030

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8J0-920-xxx-17-MY8.clb
Part No SW: 8J0 920 980 E HW: 8J0 920 980 E
Component: KOMBIINSTR. VDO H22 0130
Revision: D0H22001 Serial number: 2248G001007084
Coding: 0004428
Shop #: WSC 50811 003 1048576
VCID: 33331F110734F12F047-8066

1 Fault Found:
00003 - Control Module
005 - No or Incorrect Basic Setting / Adaptation
Freeze Frame:
Fault Status: 01100101
Fault Priority: 6
Fault Frequency: 1
Reset counter: 255
Mileage: 73528 km
Time Indication: 0
Date: 2020.03.01
Time: 00:49:03

-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels:. 1K0-907-530-V3.clb
Part No SW: 1K0 907 530 L HW: 1K0 907 951
Component: J533__Gateway H15 0180
Revision: H15 Serial number: 1400K079128465
Coding: E9801F2E1002025101
Shop #: WSC 01236 785 00200
VCID: 3039101DF622CA37795-8064

1 Fault Found:
01309 - Power Steering Control Module (J500)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 173
Mileage: 73528 km
Time Indication: 0
Date: 2020.03.01
Time: 00:49:06

-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 1K0-920-xxx-25.clb
Part No SW: 8J0 920 980 E HW: 8J0 920 980 E
Component: KOMBIINSTR. VDO H22 0130
Revision: D0H22001 Serial number: AUX7Z0G8FNE0MX
Shop #: WSC 00000 000 00000
VCID: 33331F110734F12F047-8066

No fault code found.

-------------------------------------------------------------------------------
Address 26: Auto Roof Labels: 8J7-959-255.lbl
Part No: 8J7 959 255 B
Component: 256 VSG TT H13 0110
Shop #: WSC 00000 000 00000
VCID: 3E253E253C762C47FB9-806A

No fault code found.

-------------------------------------------------------------------------------
Address 42: Door Elect, Driver Labels: 8P0-959-801-MAX1.lbl
Part No: 8J7 959 801 B
Component: Tuer-SG H02 0060
Coding: 0000565
Shop #: WSC 01236 785 00200
VCID: 3B2337312F64396FDC7-806E

No fault code found.

-------------------------------------------------------------------------------
Address 44: Steering Assist
Cannot be reached

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels:. 8J0-959-433.lbl
Part No: 8J0 959 433 B
Component: KSG H11 0080
Coding: 1890300241182D098505489AD633
Shop #: WSC 11111 111 45725
VCID: 353721090940EF1F2A3-8060

Subsystem 1 - Part No: 1K0 951 605 C
Component: LIN BACKUP HORN H03 1301

Subsystem 2 - Part No: 8J0 951 177
Component: DWA-Sensor H03 0020

No fault code found.

-------------------------------------------------------------------------------
Address 47: Sound System Labels: 8J0-035-223.lbl
Part No SW: 8J0 035 223 B HW: 8J0 035 223 B
Component: J525 Amp Std H03 0120
Revision: 00H03001 Serial number: 93802003601106
Coding: 0106137
Shop #: WSC 01236 785 00200
VCID: 2313EF51B7D461AFF47-8076

No fault code found.

-------------------------------------------------------------------------------
Address 52: Door Elect, Pass. Labels: 8P0-959-802-MAX1.lbl
Part No: 8J7 959 802 B
Component: Tuer-SG H02 0060
Coding: 0000565
Shop #: WSC 01236 785 00200
VCID: 3C21342D2A6A3E57D5D-8068

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio Labels: 8J0-035-1xx-56.clb
Part No SW: 8J0 035 186 J HW: 8J0 035 186 J
Component: R Concert2+ H04 0240
Revision: 00H04000 Serial number: AUZ1Z3G6519722
Coding: 0210101
Shop #: WSC 01236 785 00200
VCID: 33331F110734F12F047-8066

No fault code found.

-------------------------------------------------------------------------------
Address 76: Park Assist Labels: 8P0-919-283.lbl
Part No SW: 8P0 919 283 D HW: 8P0 919 283 D
Component: Parkhilfe 4-Kan H09 0070
Revision: 00H09000 Serial number: 00067824820725
Coding: 0000021
Shop #: WSC 131071 1023 2097151
VCID: 3C21342D2A6A3E57D5D-8068

No fault code found.

End----(Elapsed Time: 01:11, VBatt start/end: 11.8V/11.8V. VIgn 12.0V)-----


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## red23 (Jan 24, 2015)

Hoggy in regards to your reply on the other thread i accidentally posted the output in:

I cleared all the codes, when i disconnected the battery they all returned again. (The car has multiple other issues on top of this already)

I'll try jump start the car in next couple of days......with the cables the right way round.


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## red23 (Jan 24, 2015)

Hi all,

Sorry have been away for a while so had to leave the car issues while dealing with the obvious larger issue currently at hand.

I have just scanned the car again with my ODB11 tool and it has detected a fault, if i clear all the faults this one remains:

Fault Code 01259 - Fuel Pump Relay (J17): Open or Short to Ground

The Fuse looks ok but i will purchase a new fuse anyway (Fuse 167) as shown below - Picture stolen from another post

Could this be the problem?


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## IPG3.6 (Sep 5, 2015)

Could definitely be.

Can you hear the pump priming on door open?


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## red23 (Jan 24, 2015)

ianpgonzaga said:


> Could definitely be.
> 
> Can you hear the pump priming on door open?


Can't say i've ever heard anything priming when i open the door. Not overly sure how it should sound.

I've got a roadster if that makes a difference (believe the pump is behind the driver seat).


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## Hoggy (May 8, 2002)

Hi, If the fuse is O.K. more than likely the fuel pump relay, but no idea where it is on the MK2.
Hoggy.


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## FNChaos (Nov 30, 2016)

red23 said:


> The Fuse looks ok but i will purchase a new fuse anyway (Fuse 167) as shown below


Item 167 is a relay, not a fuse.

If I were you, I would check every available fuse for continuity with an ohm / multi-meter. This would include all of the fuses located on the side of your dash, the fuses under the hood and all of the fusible links coming off of your positive battery terminal. If you find an open fuse, be sure to note its location since you will need to isolate the cause.

You could replace your fuel pump relay, but it probably is not defective. Relays are one of the few electronic components that don't care about polarity ( there 'might' be a diode mounted across the relay's coil for reverse EMF, but if that opens it won't cause the relay to stop functioning). That said, relays are cheap so why not?


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## Wolvez (Jun 22, 2018)

Fuel pump fuse is located at the rear right fuse holder near comfort module.


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## Wolvez (Jun 22, 2018)

Clean the ground connection.


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## red23 (Jan 24, 2015)

Have checked all fuses in bonnet and driver door fuse box and all of them are fine. The rear battery terminal doesn't appear to have any fuses just the positive and negative connectors.

Also cleaned the ground wire as you suggested Wolvez - were no issues with it before i connected the battery with the reverse polarity.


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## FNChaos (Nov 30, 2016)

red23 said:


> The rear battery terminal doesn't appear to have any fuses just the positive and negative connectors.


The positive connector to your battery should contain several fusible links, including your N253 (which is design to blow and prevent your car from starting after an accident).


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## Wolvez (Jun 22, 2018)

red23 said:


> Have checked all fuses in bonnet and driver door fuse box and all of them are fine. The rear battery terminal doesn't appear to have any fuses just the positive and negative connectors.
> 
> Also cleaned the ground wire as you suggested Wolvez - were no issues with it before i connected the battery with the reverse polarity.


The fuel pump fuse is hidden behind the rear right trim.


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## red23 (Jan 24, 2015)

Ok so got out today and tested every single fuse and fuse link for continuity with a multi-meter everything perfect and no fuses appear to have blown.

All fuses in side of dashboard - ok
All fuses in engine compartment - ok
All fuses in boot behind boot lining - ok
Fuse Links on battery - ok (FNChaos - didn't know what to do or check item 7)

Did notice there is no Petrol Injector fuse (or words to that effect) which seems unusual?

I've ordered a fuse pump relay Fuse 167 from online, the car doesn't seem to detect any change when the relay in in place or not.


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## red23 (Jan 24, 2015)

fuck!! think i've found it, have ordered new link fuses from halfords, will fit them on Friday when i recieve. Didn't realise there were link fuses there. It's the 175a and 80a fuse thats blown.


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## ab54666 (Nov 18, 2019)

Good spot, they won't be helping


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## FNChaos (Nov 30, 2016)

red23 said:


> Didn't realise there were link fuses there. It's the 175a and 80a fuse thats blown.


Yeah ! Makes sense the high current fuses would blow first when you reversed your battery.
Fingers crossed that nothing else was damaged.

Make sure you disconnect your battery's positive terminal before you replace those fusible links. 
It took 175 amps to open the one. If something is still shorted, you don't want to be part of that circuit...


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## IPG3.6 (Sep 5, 2015)

eeek they're pretty large fuses to blow! careful on replacment


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## red23 (Jan 24, 2015)

Ok so replaced the fuses and still the car will not stat - i am waiting on a new fuel relay which has been delayed.

Quite worryingly a large number of bulbs in the front lights no longer work. (all lights came on when it was reverse connected) I have replaced the bulbs which stopped working and nothing only SOME of them work all passenger side bulbs won't come on except the sidelight.  Rear number plate bulbs no longer come on also.

Now have terminal 30 left - Open Circuit
Left Fog light - open circuit /short circuit to B+
LEft High Beam - open circuit /short circuit to B+
LEft Low Beam - open circuit /short circuit to B+
TErmianl 58d interior light dimmer - short ciruit to ground


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## Llewkcalb (Jul 15, 2019)

ianpgonzaga said:


> eeek they're pretty large fuses to blow! careful on replacment


Quite true! Check everything carefully.

A fuse rated at 175A would have let through an incredible amount of let energy into the circuit and potentially damaged parts including insulation.

A 175A fuse doesn't blow at 175, it is a function of current and time. Thousands of amps can flow for a very short time and blow or hundreds of amps for a number of seconds and blow.

Same applies to the 80A.

Steve


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## red23 (Jan 24, 2015)

Ok so got my Fuel Pump relay and its the same issue and error messages 

Fuel Pump Relay - Open Circuit/Short to Ground
Terminal 30 Left - Open Circuit

Car turns over as shown in video but doesn't start.

Any thoughts? Visual Check of ECU? Wires are all covered in insulation so hard to check those, anything i could check on the pump itself? any other fuses i might have missed?


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## FNChaos (Nov 30, 2016)

Terminal 30 = Battery 12v ( B+) on fuse panel 'A'. 
Fuse panel 'A' is the power rail that your two big (blown) fuses were connected to.

Fuse SA1 -175A (furthest to the left) feeds your alternator / regulator. 
Fuse SA2 - 80A (next over) I believe feeds your power steering control module.

Disconnecting your battery can cause a terminal 30 error, but if it comes back after clearing than it's a legitimate problem

Triple check that you have 12 volts on both sides of all the fuses on panel A. Also verify that you haven't blown any more fuses after replacing SA1 and SA2









If there is 12v on both sides of the fuses, I would suspect blown diodes in your alternator / regulator. and / or maybe a blown central control module, steering control module or ECM?

That said, if you don't find another open fuse I think you need to consider towing your car to the dealer (or other competent shop) as "shotgunning" control modules is going to get pricey.


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## Wolvez (Jun 22, 2018)

Try cleaning the fuel pump ground. The 1st step of 
GFF (Guided Fault Finding) is cleaning the ground connection.


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## red23 (Jan 24, 2015)

FNChaos said:


> Terminal 30 = Battery 12v ( B+) on fuse panel 'A'.
> Fuse panel 'A' is the power rail that your two big (blown) fuses were connected to.
> 
> Fuse SA1 -175A (furthest to the left) feeds your alternator / regulator.
> ...


OK so triple checked every fuse and everything appears perfect.

Fuse SA1 -175A & Fuse SA2 - 80A both have 12volts as expected (does this mean rulling out a wiring fault up to the fuse module?

I tested to see if the fuel relay clicked when switching the car on but none of them do. Should only the Fuel Pump Relay click?

I have noticed that the windscreen wipers/washers don't work either?

Since the left side light, wipers and relays don't appear to be doing anything could this be looking more like a common wiring fault?


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## FNChaos (Nov 30, 2016)

red23 said:


> I have noticed that the windscreen wipers/washers don't work either?
> 
> Since the left side light, wipers and relays don't appear to be doing anything could this be looking more like a common wiring fault?


If all of your fuses test good, then the common denominator(s) are your steering control module and your electronics control module (+ a good chance there is might be more damage found as you progress through the repair). Not likely just a simple wiring issue.

The power surge that took out your 'A' panel bus fuses was felt by every component that was not isolated when you reversed you battery. Blowing a 175A fuse is no small thing.

I think you've exhausted what you can do at home with limited skill and limited tools. Time to take it to a professional.


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## red23 (Jan 24, 2015)

FNChaos said:


> red23 said:
> 
> 
> > I have noticed that the windscreen wipers/washers don't work either?
> ...


Yeah starting to look this way. Better to take it to a car mechanic or an car electrical specialist?

Just confused as to why none of the fuses other than the 175 and 80 amp blew.

The battery was connected 4/5 times which doesn't help as it was not immediately clear the positive and negative terminals were reverse charged.

I've thought about buying a replacement ECU (ECM) to try see if i had any luck with this but i'd imagine it wouldn't controls things like windscreen wipers? If this fails i could resell it.

Would a faulty ECU stop the relays from clicking when i turn the ignition on?


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## Wolvez (Jun 22, 2018)

red23 said:


> Ok so got my Fuel Pump relay and its the same issue and error messages
> 
> Fuel Pump Relay - Open Circuit/Short to Ground
> Terminal 30 Left - Open Circuit
> ...


Disconnect the fuel pump module and check the voltage at the connector going to the 2 big terminals. *The lights are controlled by the central electric module *. Try rechecking the coding.

There are 2 404 relay. One is for the water pump and the other one is for the fuel pump.



red23 said:


>


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## IPG3.6 (Sep 5, 2015)

red23 said:


> FNChaos said:
> 
> 
> > red23 said:
> ...


I don't think your issue lays at the ecu but if you want to test your ecu you should be able to plug it into another car and scan it. Obviously it won't start that other car but at least you can test if it's good or if it's fried.

Maybe get a visual of your CECM / BCM plugs and relays. See if anything is burned out there.

I'd also triple check all the cabling, the N321 (I think that what the airbag ignited module is... or maybe I'm thinking of something else) that is near / around the battery. Is there a short there?


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## FNChaos (Nov 30, 2016)

red23 said:


> I've thought about buying a replacement ECU (ECM) to try see if i had any luck with this but i'd imagine it wouldn't controls things like windscreen wipers? If this fails i could resell it.
> 
> Would a faulty ECU stop the relays from clicking when i turn the ignition on?


Don't confuse your ECM (engine control module) J623 with your Electrical System Control Module (or sometimes called the Vehicle Electrical System Control Module J519)

Your Electrical System Control Module lives behind and under your steering column along with another relay carrier.

Unlike the old days when battery power was simply routed through switches to turn things on / off (i.e headlights, radio), Your Electrical System Control Module is basically a microprocessor that monitors and controls all of your various electrical subsystems.


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## FNChaos (Nov 30, 2016)

ianpgonzaga said:


> I'd also triple check all the cabling, the N321 (I think that what the airbag ignited module is... or maybe I'm thinking of something else) that is near / around the battery. Is there a short there?


Your pyrotechnic battery isolator N253 (item 7) fires a piston through your batteries main connection point (opening the circuit) when triggered by an airbag deployment. This is done to prevent an electrical fire in the event of an accident.
Red23 said he's check this already









To see an illustration of how one works: https://www.pyroswitch.com/function/


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## IPG3.6 (Sep 5, 2015)

Ahhhh thanks its N253. Haha I got that completely wrong! I've had one go bad even though it physically looked "ok"


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## red23 (Jan 24, 2015)

FNChaos said:


> red23 said:
> 
> 
> > I've thought about buying a replacement ECU (ECM) to try see if i had any luck with this but i'd imagine it wouldn't controls things like windscreen wipers? If this fails i could resell it.
> ...


Wow thanks for the replies guys, really much appreciated. I'll admit i'm a tad confused but keen to learn all i can.

I've not checked and modules under the steering column, can i get to it easily?

https://fusesdiagram.com/audi/fuses-and ... -2014.html - Is it the module where it says "Relay box in passenger compartment (pre 05/2009)" (my TT is a 2007)

I've checked all link fuses on the battery, but could not check anything with N253 (item 7) as there did not seem to be a way to check this?

You mentioned to check the CECM / BCM? - is this J519?

https://www.ttforum.co.uk/forum/viewtop ... &t=1531889 - this post highlights ALL components that is wrong with my car at the moment. (Fog light, dipped beam, main beam, windscreen washer pump, fuel relay, terminal 30, number plate lights)


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## FNChaos (Nov 30, 2016)

red23 said:


> I've not checked and modules under the steering column, can i get to it easily?
> 
> https://fusesdiagram.com/audi/fuses-and ... -2014.html - Is it the module where it says "Relay box in passenger compartment (pre 05/2009)" (my TT is a 2007)
> 
> ...


Thanks to the links provided by SJP, [smiley=thumbsup.gif] you can download the wiring diagram and component location manual (look for A005TT20021) Component location can be found near the end of the document. While you are there, download everything else for your reference

See: https://www.ttforum.co.uk/forum/vie...&p=9331743&hilit=A005TT*+A005TT20021#p9331743

As far as checking your pyro battery interuptor, here is a video showing where the battery connection is broken. (However, this shouldn't be your problem. It if was your car wouldn't crank as it disables the connection to you starter)


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## red23 (Jan 24, 2015)

FNChaos said:


> red23 said:
> 
> 
> > I've not checked and modules under the steering column, can i get to it easily?
> ...


Spot on have had a brief read and will read more tomorrow!! Can't wait for tomorrow now!! Removing the panels to get to J519 must be difficult???





 - have found this which may be similar?


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## IPG3.6 (Sep 5, 2015)

Yes that is quite similar - it's not as hard as you think it's going to be.

Main rule is if it doesn't easily come out with a wiggle or medium-ish pull then you've forgotten a bolt.


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## red23 (Jan 24, 2015)

Great, got in to it, all the wiring seems fine from the initial inspection.

Checked and swapped the relays around using the horn to test and checked with multimeter for continuity.

Relay R4 for terminal 30 is constantly hot, is this normal?










Is it worth purchasing a replacement from ebay? as the problems all seem to tie back to the J519 unit.

Does the wiring for J519 then tie back to the ECU?

Are they just plug and play? do i need to ensure i buy the same serial number?


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## red23 (Jan 24, 2015)

red23 said:


> Great, got in to it, all the wiring seems fine from the initial inspection.
> 
> Checked and swapped the relays around using the horn to test and checked with multimeter for continuity.
> 
> ...


Any thoughts on this lads? Purchase a new J519 module even though it looks damage free with all relays working?


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## FNChaos (Nov 30, 2016)

red23 said:


> Are they just plug and play? do i need to ensure i buy the same serial number?


Yes, you will need to buy the exact same and no, you will need to code it.

Here is a little info on the J519 module. Site references a Touareg, but the idea is the same
https://www.car-auto-repair.com/volkswagen-j519-electrical-power-supply-control-unit-instruction/


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## red23 (Jan 24, 2015)

PARTIAL SUCCESS!!

I decided to take each of the fuses out one by one and measure the actual continuity rather than buzzing the terminals and the fuel pump relay fuse in the boot wasn't giving a proper reading. Swapped with another fuse and the car started!!!!!

I still have the terminal 30 issue though..... affecting Left front fog light and Left full/dipped beam and indicator? also the rear number plate lights for some reason.

If i remove the Relay R4 which is for Terminal 30 or Connector 4 which controls the left side lights, the error codes are no different.


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## red23 (Jan 24, 2015)

Have found the wiring diagram but appears to go directly from J519 to the headlight and have been unable to find a fault on either so far. Or would this be routed via the ECU?


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## IPG3.6 (Sep 5, 2015)

are you clearing your faults before you repair, then check again? They won't go away on their own...

Yes you're correct that wiring from headlights go straight to the CECM/BCM and don't have anything to do with the ECU


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## FNChaos (Nov 30, 2016)

red23 said:


> I still have the terminal 30 issue though..... affecting Left front fog light and Left full/dipped beam and indicator? also the rear number plate lights for some reason.
> 
> If i remove the Relay R4 which is for Terminal 30 or Connector 4 which controls the left side lights, the error codes are no different.


Relay R4 isn't likely to be your problem. This relay is active when 12v from your battery (via Terminal 30) energizes the Vehicle Electrical System Control Module's power supply.

The transistor symbol on J519 indicates that the control logic is comprised of semiconductors (i.e. transistors and integrated circuits), not switches and relays. The common denominator between the the various control signals for left fog, low, high, etc is the J519 module itself. 









You could try reseating the the 10pin connector (K) or maybe opening up the control module to inspect for burnt components, but without an actual schematic of the module there isn't much else you can do.

My guess (based on the info you've provided) is the control module and / or control module power supply is defective, but without testing it is only a guess.


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## red23 (Jan 24, 2015)

FNChaos said:


> red23 said:
> 
> 
> > I still have the terminal 30 issue though..... affecting Left front fog light and Left full/dipped beam and indicator? also the rear number plate lights for some reason.
> ...


Have tried reseating all connectors with no luck. Just received a replacement ESU module with the exact part number so will try replace, any tips on recoding?


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## red23 (Jan 24, 2015)

Gent's i need to come back to say that the issue is resolved and quite honestly its embarrassing 

The initial problem with the car not starting was the fuse blown every so slightly despite double checking and even getting continuity.
2nd problem with Terminal 30?, Fuse 7 in fuse holder F was completely missing?!?!!?!? - I had discounted this because the J519 was mostly operational. Where it went i have no idea, could it have jumped out when the car was connected in reverse polarity??? as no fuse was removed between connecting the battery wrongly and using the ODB11 tool yet the fault was present.

I must thank every single one of you who helped and gave advice with this and i can now say i am far wiser with the in's and out's of Audi TT's now :lol: and now know how to use VCDS relatively well now!

Now on to fix the spoiler issue and amp drain :lol: :lol:


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