I will try to keep this short but I'm looking for some help relating to a lighting problem. A long post but it might help someone identify the issue hopefully. Skip to the last paragraph for the issue.

Basically about a 8 months ago my driver side full beams light melted and I need to replace the unit (got help here with ordering that last week). Don't know why it melted and had no warnings etc it was actually just when I went to change the bulb I saw it. 

I also have an issue with rear brake lights driver side, where they wouldn't come on or would flash rapidly, again something I didn't know until on a dark morning the guy behind me ran up at traffic lights and told me I had no rear lights. 

One evening heading home I got an engine failure warning and I brought it to the mechanic next day. No warning on once I restarted the car, he said there was a fault with one of the brake lights and took out the bulb and didn't replace it and I had no issues since.

However, now if I drive around with no light on bar the normal daylight ones I have no issue. Once I turn on my dipped lights I get the engine failure warning pops up every other time or I get loss of throttle for about 2 secs or until I take my foot off the pedal and then put it back on. This morning then when I put the key in the ignition and touched the brake(car still off at this stage) I can here a relay switching on the left hand side of the car. Is it possible this relay has been causing the issues and any idea what relay it could be. 

 

Sorry for the long post.

 

 

You need to fully remove the BCM and inspect it for signs of water ingress and/or greenish corrosion of the connector pins.

Thanks for the response, I will get at that tomorrow when it stops raining out. Is there any particular relay on it that would be responsible for the lights that I could check? 

15 minutes ago, pleasestartnow said:

Is there any particular relay on it that would be responsible for the lights that I could check? 

The Body Control Module is a fuesbox and mini computer combined. The lights (with the exception of High Beam) are usually controlled by solid state devices called MOSFET's which are not user replaceable. The whole of the BCM is considered 'non-serviceable' although there are specialist electronic companies that can repair some of them.

I was just watching a few videos on them there and the need to be reprogrammed etc. Sounds like an absolute nightmare and expensive. 

6 minutes ago, pleasestartnow said:

and the need to be reprogrammed

Yes they do require programming, but you can do it yourself with a windows laptop and FORScan software. If you have to replace it then you need the exact same part number.

Got a look today and no sign of water ingress on Orr around the BCD. Pulled out the plugs and the pins all look fine.  However, I did find water ingress in the boot, there was water in the spare wheel well which seemed to be coming in from somewhere on the right side but I could see where. Took off the rear lamp unit and it was bone dry there as well so I don't think water is getting in there. So now I'm thinking maybe there is an earth point somewhere there that the rear lights go to that could be corroded? Had to drive there in the dark with no rear lights/brake lights except the small red one on the top of the boot. Anyone have any ideas where there could be related earthing points?

So better weather today and took out the break light bulbs to test them to see if they were still working as I had no rear/brake lights last night coming home. Indicators and reverse lights work. I found the passenger side bulb socket looked damaged even though the bulb is testing as being ok. So maybe that is the problem, maybe a short occuring there somewhere. I have taken that bulb out and going to go for a spin and see am I getting the same issues. The other brake light still doesn't light up. 

Same issue, random loss of acceleration and engine malfunction/service message.

Got a friend to connect their code reader and got these errors. Fuses are all good as well.

P062b causes limp mode.  But it's an awkward code, covering many different parts.

I suspect there's a wiring fault on or near the PCM which is causing both that fault and the brake light one.

Thanks for the response. Where is the pcm located? As in is it like the bcm where I can see the wires/connector blocks so I could see any issues?

12 hours ago, pleasestartnow said:

Thanks for the response. Where is the pcm located? As in is it like the bcm where I can see the wires/connector blocks so I could see any issues?

I'm not sure on that model & engine.  It'll be around the engine bay somewhere.  It was attached to the battery box on the 1.6 TDCI Mk7 so that's probably a good starting point.   PCM's are usually under tight security to prevent tampering, so you often have to drill out rivets or snap-head bolts to access them.

Found it and as you said it's a pain so I think I will have to leave it at that. Have a new brake switch ordered so will see what effect that has when I change it

Replaced the brake switch, it cleared all the brake warnings which is good. Still have no rear lights and going into limp mode randomly when I turn on the lights. 

So today I got my hands on a replacement set of bulb holders for the rear left lights and replaced the right headlamp and so no far lights are all working and haven't had the slowdown or engine warning lamp so fingers crossed something there fixed the oroblem

 

Hey. Did you manage to solve the P062B error?