Central Locking woes

[AALocksmiths]

Hi Maelgwn,

I have had time to have a quick look into it. The fault code was coming up in the central electrics control module as well as the back door modules. It was odd that the remotes would unlock the doors but not lock them and the Lock/ Unlock on the drivers door would work them fine.

The fault code looks like it could be related from anything that talks on the CAN network as well as a damaged wire, as you know that the doors work I think it would unlikely be a wire. I'm leaning more towards the Central electrics module.

I haven't pulled one apart (Yet) so I'm not 100% sure on how it works but I'm thinking that the rear doors would work as one output, I think that it would be this which is not working. It could be from either a damaged component on the PCB, corrosion or dry solders, I have found the dry solders to be common in VAG cars so this is where I would be starting.

One way that you can try narrow this down is to unplug the CECM from the CAN and see if the fault goes away.

[maelgwn]

I haven't pulled one apart (Yet) so I'm not 100% sure on how it works but I'm thinking that the rear doors would work as one output, I think that it would be this which is not working. It could be from either a damaged component on the PCB, corrosion or dry solders, I have found the dry solders to be common in VAG cars so this is where I would be starting.

One way that you can try narrow this down is to unplug the CECM from the CAN and see if the fault goes away.

Thanks

I'm assuming you mean the Comfort Control Module?

I pulled it out and pulled it apart a while ago and there was not anything obviously wrong with it. I'm not the most experienced with this stuff but it looked fine.

When the CCM was disconnected nothing further was revealed by scanning - from memory the error was then something like Comfort Canbus Open Circuit, instead of single wire mode.

[AALocksmiths]

No, not the comfort module.

The CECM from what I have read should be above the peddles and has a couple of relays sticking into it.

I have been looking into what functions can be changed in each module and both the Comfort and the CECM have options for the door locks, so this might be why the back doors lock from the switch on the drivers door but not the remote.

I don't think that with your car the modules are coded to the car so you might be able to get both computers from a wreck and swap them over to see if that fixes it, they will most likely need to have the functions coded but that's not an issue. The other option is to remove both modules and check all the solders and connections. If you wanted I can help you out with that.

I will keep looking into it though to see which parts each module play with the locking and unlocking of the doors as that will help narrow it down.

[maelgwn]

Ok - pulled the CECM module. Didn't reveal anything and all connections look fine.

Had a breakthrough though. Noticed that when you lock the car with the key you can't open the door from the inside, however when you lock from the drivers button you can still get out. Also when you unlock the car - if you only open the back left door the car still locks itself after 30s like no one has got in.

So this lead me to the wiring harness in the back left door - it's wrecked! Noticed at least 4 completely broken wires back there ...

Happy to finally find the problem

[maelgwn]

Does anyone know a reliable alternative source of the upgraded wiring harnesses?

Its $200 and 2 weeks from VW! All the ones on ebay look like the old style/not upgraded with more reinforcement and length around the bend.