Help with major electrical fault

[RayA]

Hi guys

I am hoping you can point me
In the right direction to where to start looking. I have a w204 c200 CDi BE estate automatic RHD as it’s a UK car.

Drive home and parked up Tuesday no problems. Went out Wednesday and hit the boot release.. nothing. I thought that was odd. The central locking was working but not all the indicators blinked and on the left side of the car the brake lights blinked instead. Very odd

I got in and switched on the ignition and was hit wit a BONG noise and a series of faults. Left side tensioner out, park assist failure, cruise control, speedtronic, abs fail, traction fail, passenger air bag fail and a list more. The engine turned over and started but I didn’t drive it. The screen and audio was also out.

This would seem like a singular electrical fault, a loom short or maybe a connector failure but I don’t have any circuit diagram or an idea where to even start. Any help or suggestions would be greatly appreciated.

Regards

 

[Blobcat]

Hello and welcome,

Whats the battery voltage (with the car off)?

 

[malcolm E53 AMG]

Yes if that’s the original battery on a 12 plate definitely the place to start investigating, I would replace anyway, just done my 12 plate, Varta or Bosch are best

 

[RayA]

i Will report back tomorrow guys as I am away at the moment. The battery is in the boot so I will measure at the battery and at the link terminal in the engine compartment.

 

[Steve@Avantgarde]

I would say that there is a problem on the CAN network. Everything removed or not working is on the chassis CAN. You need to start with a STAR diagnosis test, see where the link is in the chain and then work from a wiring diagram.

 

[RayA]

Hi guys. Both the main and aux battery voltages are good at 12.5 and 12.6 respectively. I called MB to come get it and I spoke to their technician and he reckoned a CAN bus failure too. It gets collected tomorrow so I will know more Monday and will report back.

 

[RayA]

Hi guys. just thought I would give you an update. I called MB breakdown and it was towed to the dealer.

Typically the fault was gone when it got there! So they did the diagnosis on the messages and cleared it. they checked all the CAN connectors etc.

It came back and I drove it for 2 weeks and then early this week exact same problem. This time I took a video and a series of photos. Again it got towed and again when it got there no fault. However the video and photos allowed them to diagnose the most likely suspect. The prefuse box. So it is being replaced today and will let you know.