# finding ignition live



## jonjokes (Jul 18, 2005)

Ive fitted a new stereo and found it impossible to find an ignition live 12v source. All i could find was 5v and so in the end i had to fit a switch which cuts off the 12v supply to the stereo. It wasnt to bad to start off with but this switch is getting on my nerves now. Does anyone have any instructions (ahem WAK)  on how to find a 12v ignition feed?

One other little thing. My radio reception has gone shite since i changed the stereo. would this be the amplified aerial and if so any more ideas on how to get round this (ahem WAK) :-D

Any advice greatly appreciated.


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## Chip_iTT (Nov 14, 2003)

easy peasy... but you wont find it on the radio harness after 2001 model. the 5v you refer to is either the K-Line (diagnostic) or the CANBus network... putting any load on either of these is likely to prevent the car starting or at least will give strange problems.

What you need is under the driver's side dash as per the pic below....

As to the reception, yes you need to power the aerial amp. The part you need is in this thread http://www.********.co.uk/ttforumbbs/vi ... ht=antenna


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## jonjokes (Jul 18, 2005)

Once again thanks very much.


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## Wak (May 6, 2002)

Chip and all,

can I request that whenever we show this pic and advise people to tap into those big high current bolts we mention that they should have in in line fuse very close to them. :?


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## Naresh (Nov 22, 2004)

Where exactly are those relays located? When I did my install I tapped into the fusebox, fuse no. 10 I think it was (can't remember which), and that worked fine. If you do it that way, you need to tap into the side of the fuse that becomes lives with the ignition on, rather than live all the time.


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## Chip_iTT (Nov 14, 2003)

Wak said:


> Chip and all,
> 
> can I request that whenever we show this pic and advise people to tap into those big high current bolts we mention that they should have in in line fuse very close to them. :?


Its a good point Wak, and as you know I normally do make that point.... but as I was creating this reply my boss came and asked a question and I forgot to go back and add it :?


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## Chip_iTT (Nov 14, 2003)

Naresh said:


> Where exactly are those relays located?


To the right of the steering column (on a RHD) behind the lower dash cover.



Naresh said:


> When I did my install I tapped into the fusebox, fuse no. 10 I think it was (can't remember which), and that worked fine. If you do it that way, you need to tap into the side of the fuse that becomes lives with the ignition on, rather than live all the time.


Fuse 10 (Fuse 37 pre 11.2001) will do the job too, but is a different circuit. That is the S contact from the ignition switch which is key inserted rather than the actual switched ignition (circuit 15) which is on Fuse 11. Actually both sides of the fuse come live with the ignition on... what you meant was "tap into the side of the fuse that doesn't become live with the ignition on when the fuse is out". The problem with using fuses 10 or 11 is that they are rated at 10 and 5A respectively and a car radio with a good output amplifier can take 7 - 10A on its own. Personally I prefer to wire back to the main busbar with a dedicated fuse. Incidentally in a pre-2001 model Fuse 5 is the dedicated 7.5A fuse.


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## kam (Sep 25, 2003)

Ignition live (when you take the key out) is on fuse no 10 / "s-contact"


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## Naresh (Nov 22, 2004)

Chip - you never fail to amaze us on your knowledge of electronics! 

Like Kam though, I used fuse no.10 but left the S-contact unattached behind the stereo.


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## jonjokes (Jul 18, 2005)

What sort of resistance should i be looking at for the fuse. And how likely is the fuse to blow. Because if it is a possibility that it could blow easily then i think i would rather keep the switch. Its a pain in the arse but it turns it on and off every time i try......

Just read earlier posts and realised that the car is a 2001 model. So does this mean im going to find switched 12v+ behind my stereo. I would be surprised as all i could seem to find was the 5v feed.


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## Chip_iTT (Nov 14, 2003)

jonjokes said:


> What sort of resistance should i be looking at for the fuse. And how likely is the fuse to blow. Because if it is a possibility that it could blow easily then i think i would rather keep the switch. Its a pain in the arse but it turns it on and off every time i try......
> 
> Just read earlier posts and realised that the car is a 2001 model. So does this mean im going to find switched 12v+ behind my stereo. I would be surprised as all i could seem to find was the 5v feed.


Wiring diagram pre 2002, Coupe non-Bose

Wiring diagram post 2002, Coupe, non-Bose


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