No Ignition Power

R

Rick900

New Member
Hello All, firstly, apologies for invading the forum with a non-T6 (but still VW) issue, as searches led me here, and there are some similar threads re battery drain testing / alarm faults etc.

I had a battery drain on a 2012 Golf 6 1.4 TSi. Whilst testing with a meter in series on the earth lead (won't be doing that again), and everything off, closed & locked, the alarm went off. After unlocking & reconnecting, there is now no ignition power - instruments & info screen completely blank. Central locking, interior lights & sidelights still work. The beeper faintly sounds randomly. All relevant fuses are intact, and those that should have power (with key out), do. Historically, the car has had random alarm events (going off in the wee hours...).

I cannot find the issue and am contemplating replacing the BCM as a last resort, before scrapping.

Any ideas what the drain test may have spooked or damaged (may be coincidental)? I'm assuming there must be a lot of commonality between VW models, from reading several T6 posts.

Thanks for any suggestions.
 
Rick900 said:
Hello All, firstly, apologies for invading the forum with a non-T6 (but still VW) issue, as searches led me here, and there are some similar threads re battery drain testing / alarm faults etc.

I had a battery drain on a 2012 Golf 6 1.4 TSi. Whilst testing with a meter in series on the earth lead (won't be doing that again), and everything off, closed & locked, the alarm went off. After unlocking & reconnecting, there is now no ignition power - instruments & info screen completely blank. Central locking, interior lights & sidelights still work. The beeper faintly sounds randomly. All relevant fuses are intact, and those that should have power (with key out), do. Historically, the car has had random alarm events (going off in the wee hours...).

I cannot find the issue and am contemplating replacing the BCM as a last resort, before scrapping.

Any ideas what the drain test may have spooked or damaged (may be coincidental)? I'm assuming there must be a lot of commonality between VW models, from reading several T6 posts.

Thanks for any suggestions.
Click to expand...

I know little about auto electrics but if you're already thinking of scrapping it you have little to lose, with the battery connected up as normal run a jump lead from the negative battery terminal to a good connection on the engine block. See if that makes a difference.
It'll cost you nothing but five minutes, dodgy earth's can cause a variety of issues and strange behaviours.
 
DaveD said:
I know little about auto electrics but if you're already thinking of scrapping it you have little to lose, with the battery connected up as normal run a jump lead from the negative battery terminal to a good connection on the engine block. See if that makes a difference.
It'll cost you nothing but five minutes, dodgy earth's can cause a variety of issues and strange behaviours.
Click to expand...
Thanks for the suggestion, but it makes no difference...
 
Rick900 said:
The VCDS diag tool, like all analysers, needs ign power to operate
Click to expand...
Well, to be exact the tools themselves, are powered from diagnostics socket pin 16 which is always on.

Then, a different thing is whether car's CAN gateway is alive (for diagnostic communication) without ignition switched on. Anyways, T6 gateway wakes up by opening drivers door and thus communicates perfectly with VCDS without ignition switched on. Also T6 BCM is alive - central locking, interior lights, etc. work without ignition switched on. Of course, not all controllers are alive without ignition on.
 
OK thanks. My cheapie OBDII powers up but tells me to turn the ign on to read codes. I called Gendan as I was thinking about the VCDS tool, they said it needed ign power, but from what you say it should work, at least in part. But if the problem is with one of the controllers that requires ign power...
 
Ok. It seems that in your Golf the CANbus gateway is powered also from ignition on (terminal 15) so diagnostics connection won't work right away.

Chain of command:
Ignition key is controlled by Steering column electronics control module -J527-.​
J527 connects to the BCM -J519- (labeled as Vehicle electrical system control module -J519-)​
J519 drives the Terminal 15 power supply relay -J329-​
​
Thus all of them need to alive​
​
To force ignition on (to enable further diagnostics) you could bypass J329 simply by shorting the relay (J329) terminals 30-87 (pins 3-5) of thw relay.
1771919729606.png
 
Thanks, I'll check later, but if J329 is the left most one in the relay block under the BCM, I have already and no lights came on. Identical symptoms reported on the Briskoda forum was caused by an ign switch fault, but I don't have power on any of the 4 wires to it. On the steering wheel module, there's only 1 live wire in (will add references later).
 
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Rick900 said:
J329 is the left most one in the relay block under the BCM
Click to expand...
That's correct I believe (as for some reason my diagram doesn't distinguish LHD/RHD. I think relay is of type 645.

Rick900 said:
I don't have power on any of the 4 wires to it.
Click to expand...
Strange 🤔 - there should be power via SB7 (as the SB7 is the only thing between battery and the relay).
 
It is a 645, there are 2 of them. The left one has power to 1 & 3. Previously I've linked 3 & 5, there was a current draw but nothing seemed to happen, will try again.

Sorry, the 4 wires I referred to with no power, are the ones into the ignition switch from the steeringwheel module.
 
Rick900 said:
It is a 645, there are 2 of them. The left one has power to 1 & 3.
Click to expand...
Strange as pin 1 is ground, BCM drives pin 2.

Rick900 said:
Previously I've linked 3 & 5, there was a current draw but nothing seemed to happen, will try again.
Click to expand...
Quite possible as many controllers, e.g. dash, probably need also "wake-up" signal.
 
Confession time. Checked the SB fuses against wiring diagram, noticed F6 was blank, but listed as instrument cluster module. Put the 5A that was in F5 in F6 and bingo! All came back to life.

When I was removing fuses 1 x 1 to check drain, I must've put F6 back in the F5 empty slot - what an idiot!

Thanks very much for your time looking into this, sorry it was wasted...
 
Excellent result dancing.gif
Learning from mistakes and all that. Thanks for sharing, appreciated :thumbsup:
 
Rick900 said:
Confession time. Checked the SB fuses against wiring diagram, noticed F6 was blank, but listed as instrument cluster module. Put the 5A that was in F5 in F6 and bingo! All came back to life.

When I was removing fuses 1 x 1 to check drain, I must've put F6 back in the F5 empty slot - what an idiot!

Thanks very much for your time looking into this, sorry it was wasted...
Click to expand...
Not the 1st and won't be the last.
I bet you've now thought you should have taken a pic 1st? 😁
 
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