# Wont start - weird going ons



## darren1984 (Jan 30, 2017)

Hi, I wonder if anyone can help.

Lisa (my other half) parked her MK1 V reg TT on friday after work. Her car sat all weekend as we use my Audi as a family car.

So here's what happened. Monday morning I get a call, her car wont start, only turns over, she kept trying and killed the battery. I came home, hooked up the jump leads, car still cranking but not any sign of firing up.

Checked the obvious things, spark and fuel and it would seem we dont have either, checked the plugs buy taking them out, pusing back into caps, touching against the rocker head metal casing and turning the key. No Spark.

Pulled the fuel line off from where it enters the injector metal hose (rubber pipe left hand side, you facing the car) had a friend turn the key, no fuel shooting out as I would have expected. I checked the relays for fuel pump and ECU and both can be felt clicking when ignition turned on. Can also see voltage when using my meter.

I changed the relay anyway (marked 428) under the hood near the bulkhead. Nothing.

Decided to get a friend, ex Audi dealer mechanic to come along with his VAGCOM, turns out it wont connect, it just says communication error. Tried it on my A4 and connects in a matter of seconds.

He thought it may be the ECU as VAGCOM can connect to ABS and airbag ok.

second hand ECU arrived today, same code on the top exactly. From same year and model. Expected maybe to need de immobilised but thought the car might start first before cutting out. Turns out on first turn of ignition the immobiliser light goes out anyway on the dash as though the car is happy, but it will still not start, there is no life in the car what so ever.

Decided to change the crank pos sensor today, never made a difference either. The old one though was pretty carboned up so happy to have changed it.

I've ran out of ideas now. Has anyone had a similar issues, any pointers. Car has sat now for 2 and half weeks

thanks very much

P.S checked all the fuses in the right hand side of dash

Note: from dropping the under side of dash drivers side I can see an old nokia hands free kit, the car also has an aftermarket stereo. Just in case you need this info re the vagcom not reading.

Cheers

Darren + Lisa

Is there anything else I can try


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## Hoggy (May 8, 2002)

Hi, Have checked relay No2, marked 100 (j271) in relay box under bonnet.
Hoggy.


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## darren1984 (Jan 30, 2017)

Hoggy, hi

That relay does not exist in this car. There is no relay in that position. I even pulled the box/bracket apart to see if maybe it had fell through. But there is nothing. Should that definitely be there?


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## Hoggy (May 8, 2002)

darren1984 said:


> Hoggy, hi
> 
> That relay does not exist in this car. There is no relay in that position. I even pulled the box/bracket apart to see if maybe it had fell through. But there is nothing. Should that definitely be there?


Hi, It is in the Bently manual & others have had the same problem & found that relay was the cause.
Have you checked fuses No.10,28,29,32,34,43 with a meter, not just by eye.
After market radio can cause no contact with VagCom.
Hoggy.


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## outdoor stevie (Nov 24, 2013)

Can you hear the fuel pump priming when you turn the key before you actually start it? Should hear it as it's under the rear seat driver's side, if not then check the connector on the top of it for power when the key is turned, fuel pump relay is under the driver's panel by your shins, worth checking just in case.

Stevie


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## darren1984 (Jan 30, 2017)

I've not checked the fuses for voltage, only by eye so thats tomorrow's job.

I don't hear the fuel pump prime when I switch ignition on. I will check this tomorrow also.

Thanks for the help guys, really appreciate it


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## rusTTy_racer (Sep 7, 2015)

As above + when cranking can you see the rev counter rise to 200-300rpm?

Is it a Quattro? know issues if your second fuel pump fails so cuts out with 1/4 tank of full left.

Ensure ignition switch functions and relays work.

Confirm drain hole not blocked on fuel filler cap that may allow water into tank/is it a roadster? possible problem with kan wires that was in a thread last week. Hope you get it sorted


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## dox (Oct 24, 2013)

Non start, no spark, no fuel and unable to connect vcds, is the ecu getting powered up?

Did you try the spare key with the original ecu?


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## bravozero (Oct 4, 2014)

This may sound silly, but is there definitely fuel in the car? :?


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## chilli01 (Apr 8, 2016)

Sounds the same that happened to mine same symptoms anyway,

Mine was the Coil pack wiring was frayed and had been shorting out on the bulk head and further down the wiring loom, But there was a fuse that just went as soon as you went to turn it over, I can't remember the fuse number off hand but was located on the drivers side inner door, might be worth another check,

Hope you get it sorted mate :?


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## darren1984 (Jan 30, 2017)

Will be looking at all options today guys. Few points to help any suggestions.

1.car is a quattro
2.Fuel in the car but might only be a quarter tank to be fair.

How do I tell if the ecu is powering up?

Will keep you posted

Thank you all


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## dox (Oct 24, 2013)

darren1984 said:


> Will be looking at all options today guys. Few points to help any suggestions.
> 
> .
> 
> ...


Ask you tech friend to check if for you?

ABS and air bags have there own ecus, you can connect to those so it looks like the ecu isn't getting power, fuses , relay, ignition switch etc

Good luck


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## outdoor stevie (Nov 24, 2013)

Easy check to see if the fuel pump is getting power to it as all you do is remove the rear seat then a metal cover plate then you will see the top of the pump in the tank, electrical connector is on the top of the pump, disconnect and test for current when the key is turned to power , if no power then the issue is wiring, relay or fuse related if you are getting power then it's probably the fuel pump, you will need a system of removing fuel from the tank before you go in as any spilt inside the car will stink for years so think big container hose method of removal. The big rubber washer on the top of the pump may not go back on once it's removed so think about getting one before you go in(TPS have them). Carefully fold up the level sensor arm before removing and then you can test the pump on a bench with 12v. It's a fiddley wee job so be careful with the bits and bobs.

Stevie


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## higsta (Nov 29, 2011)

Hello buddy,

I had the same symptoms as you in my old 225 and it turned out to be my fuel pump - not an electrical issue, the thing had just seized.

The car would start if you gave the pump a wack with a rubber mallet which is obviously no use long term but it did let me get the car home!

Changing the pump is an easy DIY - I googled for a how too and it took me 30 minutes. I could of done it quicker but had to empty the tank first :roll: I think you will be OK if you say you have 1/4 of a tank. Typically I had just filled up :lol:

Good luck!


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## dox (Oct 24, 2013)

outdoor stevie said:


> Easy check to see if the fuel pump is getting power to it as all you do is remove the rear seat then a metal cover plate then you will see the top of the pump in the tank, electrical connector is on the top of the pump, disconnect and test for current when the key is turned to power , if no power then the issue is wiring, relay or fuse related if you are getting power then it's probably the fuel pump, you will need a system of removing fuel from the tank before you go in as any spilt inside the car will stink for years so think big container hose method of removal. The big rubber washer on the top of the pump may not go back on once it's removed so think about getting one before you go in(TPS have them). Carefully fold up the level sensor arm before removing and then you can test the pump on a bench with 12v. It's a fiddley wee job so be careful with the bits and bobs.
> 
> Stevie


You can test the pump in the car, remove the inspection plate, remove the wiring connector, there are 4 male spade connectors on the pump housing, 2 large for power and earth, 2 small for the gauge. Look closely and you'll see + and - on the white plastic connect to 12V and you'll hear the pump run.


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## darren1984 (Jan 30, 2017)

Hi guy, so the fuel pump connector is off and I am gettting no reading for voltage. At the fuse (side of dash) i am reading just shy of 2 volts at the fuse. Would this be correct? so a small voltage to switch the relay on which then throws the 12volts to the pump?

Can anyone tell me which relay it is and if this part will be available at eurocar parts?

Cheers


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## dox (Oct 24, 2013)

darren1984 said:


> Hi guy, so the fuel pump connector is off and I am gettting no reading for voltage. At the fuse (side of dash) i am reading just shy of 2 volts at the fuse. Would this be correct? so a small voltage to switch the relay on which then throws the 12volts to the pump?
> 
> Can anyone tell me which relay it is and if this part will be available at eurocar parts?
> 
> Cheers


A relay is a heavy current (amps) switch, 12V low current switches on 12V high current circuit.


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## pugster71 (Mar 15, 2015)

There fuse here see if its ok.
Battery compartment .


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## outdoor stevie (Nov 24, 2013)

So you have the fuel pump electrical connector off and in one hand, you then probe the two outer terminals whilst the ignition is switched on you should then get a reading briefly as the pump pressurises if you get a reading then power is reaching the pump if not then power is getting stopped somewhere along the way. Relays are above the brake pedel there are two sets of them you need the smaller of the two sets. It's a one line relay box with spaces for six relays horizontally the fuel one is fourth from the left hand side. I would have thought they were available from parts suppliers.

Stevie


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## darren1984 (Jan 30, 2017)

So does anyone know, fuse 28 says fuel pump. If i take this 15 amp fuse out, which looks good, should i be getting 12 volts here with ignition on? I'm only seeing 1.7volts? Took the wiper fuse out and can see 12 volts straight away.

Might be getting somewhere, fingers crossed.

Eurocar parts have ordered me the realy, will collect and fit tomorrow


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## outdoor stevie (Nov 24, 2013)

I would have thought that 12v should be present but haven't come across this particular issue so you may be getting there so keep on the trail!

Stevie


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## auspicious_character (Sep 4, 2016)

This is a common mk4 golf problem and the solution has been mentioned.
There is no ECU power so you're never going to get fuel voltage.
You're chasing the wrong area and you need to focus on getting vagcom to connect.

Too early to be point specific as my mind is working on diesel's atm but you need to change the ECU relay (four pin 109) or diagnose by giving a battery 12v to the white/black wires on the left hand of the ECU plug.


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## darren1984 (Jan 30, 2017)

Hi, quick update. Fuel pump relay did not fix it. I did notice however that the wire coming from the fuel pump lead had insulating tape round it, not factory. So decided to remove it. Now even more confused.

I now have an extra black wire with a dodgy solder on it which seems to run to nowhere. Is this someone taking a 12v supply for an amp at some stage of the cars life, or a diy wired immobiliser?

See the pictures


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## rusTTy_racer (Sep 7, 2015)

Might have had a tracker fitted years ago (mostly use black wires for connections IIRC) you will just have to follow the wires back to find out


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## darren1984 (Jan 30, 2017)

Great, seat backs and interior trim off then. It's nearly a shell I've got 

In regards to the previous comment about the fuel pump not getting voltage if the ecu has no power, is this true. I'm getting voltage on the ecu cable where it plugs into ecu but how would I check the ecu is powering up?


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## rusTTy_racer (Sep 7, 2015)

Have a look for something that would be powered from the ecu like a sensor connector you can check for an output.

There was a post on here recently where a mouse or squirrel had eaten some wiring under the bonnet, worth double checking  Are you able to crank it now or is it doing nothing? IIRC the fuel pump only gets a quick pulse when ignition on and then goes off till you crank/engine starts. You should be able to confirm fuel pump works easily enough by pulling of the FLOW from the fuel rail (with caution lol :wink: ) You do have a fuel filter under the car but sounds like you have more important issues to resolve. Don't rush through stuff to quickly or you may miss the obvious :?


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## darren1984 (Jan 30, 2017)

Car cranks no problem, everything seems normal when you turn the ignition on, it just won't fire. There is no fuel as already checked the fuel hose and cranked the engine. The fuel pump does not prime. I'll check a sensor tomorrow that runs from ecu. Any recommendations as my best bet to try? Thanks again everyone,


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## rusTTy_racer (Sep 7, 2015)

If you have a Bentley manual worth checking if MAF, camshaft sensor and injectors gets volts when ignition on/cranking?

So when you crank it have a look at the rev counter... does it rise to 200-300rpm or stay at zero? :? If you put your headlamps on and crank do they go out or is the battery up to the job?

Worth re-checking all the fuses and links for corrosion also clean up the earth post/ring terminal next to the ecu


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## darren1984 (Jan 30, 2017)

Battery is starting to die on me from all the cranking and checks so excuse the voltage reading but......I get voltage through this pin at the relay marked 428. But it seems not I've of the relays pins goes into this. From the bottom its a thinner red wire. No voltage at any other point. Is this the issue? Ecu not getting voltage?

Cheers

Darren


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## darren1984 (Jan 30, 2017)

Been out all day on it, no joy. Looks as though all the wiring loom has been out this car before (new engine maybe) as alot of the loom was taped up and held on to other bits with cable ties.

Will give it one more day and then it looks like its getting scrapped


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## Pow3rL3ss (Dec 15, 2008)

Sorry to be a vulture, if you scrap it can I buy the turbo please?


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## Hoggy (May 8, 2002)

Hi, I still can't understand why you don't have Relay marked 100 in the under bonnet relay box & did you check all the fuses I mentioned with a meter ?
Hoggy.


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## outdoor stevie (Nov 24, 2013)

Now bear with me on this ok and keep an open mind! What about running a feed wire from the switched live terminal under the steering column near the fuel relay on the bar direct to the fuel pump. This will bypass where you think the issue is and should power up the fuel pump and might just fire up the car!!!
This will make you feel better straight away and take the pressure off, it's a switched live and if you put a fuse inline then that should be ok. I'm not saying its a permenant fix but if it works then that's all well and good and you can still try and solve the bigger issue at your leisure, have a think about it and it'll cost nowt to try, what have you got to loose?

Always thinking

Stevie


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## darren1984 (Jan 30, 2017)

If scrapped turbo will be for sale.

I only have one relay under the bonnet. I've ripped out all the air filter box and checked all the wiring running down the plastic boxing. Everything seems okay, will take the battery out and remove the battery tray to see where they go.

Leaving the fuel pump for now as I'm not getting anything from the relay 428 under und bonnet.

I believe the ecu is not getting power at all. Just can't see why.

Battery is fully charged now for further trouble shooting tomorrow.

Will keep everyone posted

Total nightmare


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## Hoggy (May 8, 2002)

Hi, Is your engine the early APX type with secondary air pump ? According to Bentley manual relay 428 is for secondary air pump.
Hoggy.


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## darren1984 (Jan 30, 2017)

Hoggy said:


> Hi, Is your engine the early APX type with secondary air pump ? According to Bentley manual relay 428 is for secondary air pump.
> Hoggy.


There is an earlier post showing the bentley manual is wrong about thise relays and its the other way round. But this said, I still only have one under that cap in the engine bay as per my photo further up. Obviously I've just popped it out so I can inspect it.

Our TT is an old v reg so it'll be the earliest of the engines that went in the tt's. I can't remember the code even though I saw it on the block today. Stressed


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## pugster71 (Mar 15, 2015)

Wrong picture in Bentley... or right picture, wrong description (it all depends on how they're installed in your car: like this or like this)
Anyway,

428 is definitely the ECM (J271) relay.

100 is definitely the SAI (J299) relay

irrespective of their position.

This could be irrelevant what ive found this whilst looking ,if the 428 relay is goosed or the supply isn't there the ECM won't fire the car do a direct bypass as outdoor steve suggest and trace the wiring to ECM could be a short somewhere only trying to help goodluck with it.


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## rusTTy_racer (Sep 7, 2015)

Is 428 a standard 4 pin relay with nothing fancy in it? Why not make up a jumper lead with a fuse in it just in case and link it across so you know power is getting to the ecu? Would that work?


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## gerontius (Aug 27, 2016)

I don't have any experience of this fault specific to the TT, but generically, you need to be looking for a common factor giving no fuel & no spark.

A fueling fault won't stop it sparking.

More likely ECU main power feed, or crank/cam sensor failure so the ECU does not realise the engine is cranking over, thus no fuel or spark.

You need the pin-outs on the ECU to check it's being powered up with the ignition on. If not, also explains why VCDS can't read it either.


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## darren1984 (Jan 30, 2017)

Going to jump the relay today. See what happens. I think that's the issue. Fingers crossed.

The reason I hadn't tried this earlier Is that I tried replacing this relay, but I guess it could be the relay is not getting the voltage to close the circuit.


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## Hoggy (May 8, 2002)

Hi, All I can remember someone had the same problem & relay 100 was the cause. Can't remember it it was an APX or BAM engine. Still find it strange that you only have the 428 relay & not the 100. One has to supply the ECM & the other the SAI so one or the other doesn't work
Hoggy.


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## darren1984 (Jan 30, 2017)

Hoggy said:


> Hi, All I can remember someone had the same problem & relay 100 was the cause. Can't remember it it was an APX or BAM engine. Still find it strange that you only have the 428 relay & not the 100. One has to supply the ECM & the other the SAI so one or the other doesn't work
> Hoggy.


See photos attached. I've stripped it back to show what wires I've got.

There is nothing at all for relay 100. Tried bridging the relay, nothing. Engine code AJQ.

Sunday is the last day I spending time on this. I'm admit defeat. She needs a car for work and is going crazy lol


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## dox (Oct 24, 2013)

A couple of hours of an auto electrian time won't cost the earth


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## darren1984 (Jan 30, 2017)

dox said:


> A couple of hours of an auto electrian time won't cost the earth


Car being collected by trailer tomorrow, getting dropped off with my friend (audi specialist)

Before he comes I will check silly things like cam sensor and timing belt.

If and when fixed. I will post exactly what happened and what we done.

Thank you everyone


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## Hoggy (May 8, 2002)

Hi, Cam posn. sensor won't prevent it from starting.
Hoggy.


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## gerontius (Aug 27, 2016)

Isn't relay 100 on the panel above the drivers footwell - like this picture ? ::

viewtopic.php?f=2&t=315934


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## Hoggy (May 8, 2002)

gerontius said:


> Isn't relay 100 on the panel above the drivers footwell - like this picture ? ::
> 
> viewtopic.php?f=2&t=315934


Hi, No that is Load reduction relay J59, according to Bentley Manual.
Hoggy.


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## Garys-TT (Jan 8, 2017)

Every time I see that this post has been updated I hope in anticipation that you've found the problem. You've been able to check a lot more than I ever would have known how to...though I've been learning as you've gone along.

Hope it's sorted and turns out the be something simple.


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## darren1984 (Jan 30, 2017)

Another mate, (Renault truck) mechaninc, has said its simply the ignition supply to the ecu and that all he needs is a wiring diagram from ecu. Car is away now to be looked at tomorrow. I'll let everyone know what the fix was as soon as we know.

Thanks


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## darren1984 (Jan 30, 2017)

Well, we gave up. Enough time spent on an old car. Fuel pump worked fine if hooked direct to 12v.

There was definitely something wrong between the ecu and it sending signals out for spark and pump. Traced all wires from ecu, no frays or broken wires.

Hate defeats. Especially from a car that worked one day and not the next.

Thanks for everyone's input.

Darren


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## darren1984 (Jan 30, 2017)

UPDATE.....

The car is alive and running great.

I found another chap with exact same problem and a member of this forum said we should try running a direct 12v feed into the ecu feed by finding the wire he described.

To do this I had to unwrap the tape from the ecu connector. Now in honesty I only unwrapped about 2 inches. The chap who also posted this issue unwrapped more and found a broken wire. I decided to look further down, maybe only 3 inches and there it was. It was a thicker red wire which was joining a smaller red wire in what can only be described as green rot, like a rotten rubber/plastic shrink connector. These 2 wires were meant to be running into the very slim red wire via this shrink connector. Pulled all the green rotten rubber of, stripped wires back, joined, soldered, heat shrank it, taped it all back up. Turned the key, car runs great. Infact its running better. Maybe this is because the connection at the ecu is better or the fact I changed the crank pos sensor. Old one was very carbonated.

Anyway, seems like this is a very weak link and will assume every wiring loom has this connector. I'd be checking this first for anyone having issues.

Even intermittent connections through obd, this may be the cause.

Thanks again everyone.

Hopefully I can help someone else who develops this issue,

Fantastic forum, great advice


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## longodds (May 8, 2014)

Whoop Whoop. I've been watching this post and pleased you've found the problem. Well done to you and all involved!


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## SC0TTRS (Oct 23, 2016)

Thanks for spending the time to update the post  Another problem solved which I have no doubt will help someone in the future. 8)


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## Delta4 (Jun 19, 2015)

Indeed it will, i'm going check my loom at the weekend and block off the vent holes in the scuttle that's above the loom to keep the water out as a preventative measure


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## darren1984 (Jan 30, 2017)

Definitely worth checking your wires. It's the larger connector of the 2 and just unwrap about 6 inches. You should see 2 red wires running into one. I think they had a green strip. This joint rotted to the point it was hard to tell what it was. Green, grumbling in my fingers. Good luck anyone else who finds this issue. Hopefully it'll help someone else.


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