Broken down need help!

[Geeky Philip]

I am in a service area on the M6 waiting for an AA tow truck, which is a 3-hour wait.

I was driving along, and the airbag light came on, and then the central locking started locking and unlocking rapidly. This was followed by the speedo and rev counter stopping and all the warning lights coming on. The vehicle kept driving and I got into the services which were just a mile away. I tried restarting the engine which does start but then stops straight away. The AA could not get any comms on the OBD2 port, so were unable to diagnosis the error. They did check all the fuses including those under the starter battery.

I think this is a can bus error but I am hoping someone may have experienced this before and can give me some tips on how to solve this. I do have VCDS.

This van is a 2016 EURO5 T6 4Motion T32 CAAC 140

Thanks in advance

 

[roadtripper]

Not helpful straight away but if you have a major electrical issue across several systems remember to also consider checking the ground side as well as the supply side - there is a long thread of odd behaviour somewhere that was eventually traced by the owner to be a bad ground bolt.

 

[JoshB_]

Reminds me of when I tried to jump a car once upon a time with the leads on the wrong way around…
Is it converted in any way? Wonder if a battery positive has come loose and shorted itself?

 

[CJW]

BCM crapped out maybe?

Starting then stopping straight away could be the immobiliser. It’s what happens to mine when I forget to disable it.

 

[PhillH]

Sounds like a BCM issue to me, or water ingress somewhere. Worth checking all connections.

 

[JumpShip]

Gonna go with it being a loose wire somewhere.

 

[DaveD]

Not helpful straight away but if you have a major electrical issue across several systems remember to also consider checking the ground side as well as the supply side - there is a long thread of odd behaviour somewhere that was eventually traced by the owner to be a bad ground bolt.

Try a jump lead from the negative on battery to a good connection on the body or engine?

 

[Geeky Philip]

Thanks for all the replies.

I have just gotten back and unloaded the tow truck vehicle. I will start investigating tomorrow.

 

[PhillH]

How are you getting on @Geeky Philip ?

 

[Geeky Philip]

How are you getting on @Geeky Philip ?

The next day I cleared the faults with VCDS which were all communication errors. Everything was fine for about 15 minutes then the airbag light came on followed by all the other warnings. I have tried unplugging the airbag controller (below gear stick) but this does not stop the other faults.

Does anyone have any good tips on finding what is killing the can bus?

 

[PhillH]

For it to clear and go away like that I would be checking earths and connections. I would have thought if it was the BCM that the faults would be there all the time

 

[Geeky Philip]

For it to clear and go away like that I would be checking earths and connections. I would have thought if it was the BCM that the faults would be there all the time

Do you have some pointers of where the earth points are for me to check? There is very little wiring in the rear of the van, just the lights and locking cable.

 

[PhillH]

As someone mentions above, run a jump lead from your engine to your negative on your battery. Check the positive terminal is tight. Check all fuses are pushed in correctly. Any work carried out recently?
Check the plugs on your BCM are pushed in and locked in.

 

[Bigsidavies]

Do you have some pointers of where the earth points are for me to check? There is very little wiring in the rear of the van, just the lights and locking cable.

The earth point that caused me all the problems as mentioned by @roadtripper above, was the one under the centre console area below the gear lever. It’s on the van floor below all the lower dash trim.
However, my symptoms were that all the door open symbols were on the dash along with oil warning light and fail to start.
I’d removed that earth when I covered the cab floor in sound-deadening, so my own fault, but it took it 4 years to work loose.
If the earth trick with the jump lead (above) doesn’t work then maybe check the wiring diagrams for the location of the factory earth studs and check them one by one, especially if your van is converted.

 

[sams-vans]

I would check the condition of the battery as well. Vehicle computers misbehave when voltage drops. And cold weather like we just had kills batteries.

 

[roadtripper]

Do you have some pointers of where the earth points are for me to check?

As you have VIP membership you can get to the earthing concept diagrams, I think you are a T6 so this should be the right one:

https://www.t6forum.com/threads/earthing-concept-wiring-diagram.28953