immobiliser problems...

[Jimmy Filth]

I wasn't sure which section to put this in, so thought I'd put it here and if it is wrong, I'm sure it will be moved to the correct place.  Sorry mods.

I've also searched the forum and can't find the answers I'm looking for.

My immobiliser and radio are both playing up, just wanted to know if anyone had any knowledge of electrics and whether these two problems are linked.

Firstly, my radio is a pioneer aftermarket unit that has no memory once the car is turned off.  Just won't remember anything.  It will also randomly stop working.  It is currently only working 50% of the time.  At first I thought it may be a lose connection and bumps in the road may knock a wire lose, but it will turn off and on again while the car is sitting still but engine running.

Then the immobiliser/alarm.  I've been having problems with the fob since I bought the car, but cannot seem to find a place that can replace this.  Sometimes it acts like the key is dead, others like it's brand new, the problem with the immobiliser is this;

I go out to the car and using the fob (if it works) turn the alarm off, get in the car and put the key in the ignition.  All good so far.  I then turn the key and the immobiliser kicks in.  Every time I try to turn the engine on, but then turns itself off when I stop trying to start the car.

Anyone heard of this??

[SoundillusioN]

The stereo sounds like it's been wired incorrectly, the way most numpties end up doing it. Apologies if you wired it!  there are usually two live feeds required for a modern stereo, 1 which is connected to an ignition live so the stereo turns on and off with the key, the other should be constant from the battery to keep the memory going when the ignition is off. 

My guess is that the two lives for the stereo are wired together and to ignition only.... with it being temperamental I would be concerned there is something else up with the way this has been wired too.  It may not be getting enough power to run properly either, pull it out, check the condition of the wiring, check the source of it's earth while you're at it.


Immobiliser.... Hmmmm, feck knows. But mine did this! Check my project thread! 

Before I even try and suggest what it might be, do you know if this was fitted by a pro or the last owner, neither means it would be a good job by the way as mine was originally done by a pro.... ha!

Again this sounds like a power issue, you try to start the car, at this point the immobiliser power may be weak or non existent thus causing it to reset....

After a harsh change of climate, is your battery OK by the way?

[Jimmy Filth]

It's a VW alarm/immobiliser, I have checked with VW themselves and the guy I spoke to had worked for VW since before my car came out and remembered the alarm, but advised that they stopped making it. 

The battery seems fine in every other way, when the immobiliser isn't playing up starts first time and no other issues.

The car was VAGCOM'd a little while back and the only fault code was an intermittent lack of power to the airbag...

I guess I'll take a look at the back of the headunit.  Damn I hate electrics...

[SoundillusioN]

It's a VW alarm/immobiliser, I have checked with VW themselves and the guy I spoke to had worked for VW since before my car came out and remembered the alarm, but advised that they stopped making it. 

The battery seems fine in every other way, when the immobiliser isn't playing up starts first time and no other issues.

The car was VAGCOM'd a little while back and the only fault code was an intermittent lack of power to the airbag...

I guess I'll take a look at the back of the headunit.  Damn I hate electrics...

That concerns me then, not everything will appear on VAGCOM..  the fact you have had something come up reporting a fault with intermittent power suggests there could be something wrong with some live feeds somewhere... might be worth getting voltmeter around all the major feeds in your car and see if you can trace the fault?

[Jimmy Filth]

Hmmmm, that's not something I've ever had to do before.  Is that something any car mechanic can sort out???

[Tabx808]

I agree with the stereo wiring. Somewhere along the line the perm live has been disconnected and the stereo has been wired into the ignition live. Or if you still have the iso plugs (think it may depend on the year) then on most aftermarket stereos the ign live and perm live can be swapped over. This is because even though iso plugs were supposed to be a universal fitment across car ranges and stereos a lot of manufacturers swapped the ign live and perm live over. Once you get the stereo out if its just cut and joined then I would redo all the connections to make sure it secure and nothing can short out. When I bought mine. went out the next day to a flat battery. Turned out the stereo had been wired into the perm live only and the igntion live was still bared off and hanging around. And about two miles of insulating tape that seemed to miss all the actual twist joins!

Id go with SoundillusioNs advice and def get an auto electrician to check over the wiring if you are not comfortable doing it yourself. I know I wouldnt be. Im a sparks but car electrics baffle me mostly. Can do your stereo though if you want some help and i have a multimeter. your not far from me.