Car acts possessed

[Johnfc2017]

Hi,

 

The car has done this before, and I solved the problem by removing the battery and charging the battery overnight. I recently bought a new battery and tonight the car has started doing it again.

 

The symptoms are:

• The car shows dashboard lights
• The wipers moved when they aren't switched on
• The engine tries to crank without a key
• The alarm goes off.
• The windows roll down.
• The remote control is inoperable.

 

I've pulled off the negative cable on the battery so the car is dead

[fabia88]

It may be worth having a look at the wiring in the engine bay and see if there is any damage, sometimes rodents can get under the bonnet and chew through wires causing problems.

[Wonky]

Are all of these functions managed by the convenience module?
I believe there have been similar threads with similar faults as yours due to issues with this module. Possibly water ingress or corrosion of the cables. 
May be worth a search of the forum.

[mixmax]

Yeah, had similar issues, recently: windows rolled down randomly, wipers and turn signals didnt work properly, lost power to dash. Replaced the convenience module and all was fixed.

[Johnfc2017]

I plugged my carista OBD in and ran a diagnose and these errors came up. I'm guessing these are coming from either the ECU or the convenience module? It's stopped raining and the car seems okay at the moment of testing but I don't trust it. I'm taking it to an auto electrician to see what they can do.

[Johnfc2017]

This problem seems to only happen when it has been raining, so I've driven today with no problems so there must be a water ingress problem somewhere, either in the loom or the ECU or convenience module, but the driver's side is not wet.

[Johnfc2017]

I had a look inside the convenience module to see if anything was corroded but it all looks okay. I've seen pictures of waterlogged damage and there seems to be nothing visually wrong with the board.

[Johnfc2017]

Could the door wiring throw the same errors? I noticed in the diagnostic that there is a problem with the door module, so if water had got into the wiring, could that provide a communications problem across the whole CAN network?

[chimaera]

14 minutes ago, Johnfc2017 said:

Could the door wiring throw the same errors? I noticed in the diagnostic that there is a problem with the door module, so if water had got into the wiring, could that provide a communications problem across the whole CAN network?

Very much so. A friend's Octavia had this sort of problem several years ago when water from a leaking rear washer got into the trailer module and shorted across the CAN lines. Once it had dried out everything returned to normal. I'd go looking for water in any of the control modules that are connected to the CANBUS (which is probably all of them), starting with the ones in the engine bay (ABS and engine) as they're the ones most likely to get wet when it rains.
 

 

 

[Johnfc2017]

Hi,

 

I just prised open the driver's door loom to find 5 broken wires, 4 are visible in this shot and there was some water in the bellows. I've realised I can lock the doors with the remote, and lock the driver's door with the key and the car is secure until I can get the wires rejoined.

 

The red and white wire must be the supply for the window motor, which would explain why the motor didn't work.

 

I'm hoping that resolves the issue.

[Wonky]

Yes, Red and white looks to be the main supply in my Haynes manual.

 

 

[Johnfc2017]

There are 4 small wires that had broken, one had broken inside the sheathing and a number of brown wires have nicks in them. Notably a blue and brown wire that provides the CAN bus to the door module has a nick in it, which could explain the errors on the bus. The red and white wire carries 12v and is fused at 25A, so could explain why things were behaving odd when it rained, it was potentially shorting out. It may have been playing up for some time while this wire was breaking.

 

I have some liquid tape that I will be sealing the nicks with, and some waterproof heat shrink butt connectors that melt solder into the joint when heated to patch the wires together. I'm waiting on the larger sized ones for the red and white wire.

 

 

Edited 9 March, 2020 by Johnfc2017

[Johnfc2017]

Unfortunately, since 9th March, a harsh wind caught the door and smashed the connector, so I ordered a replacement connector and wires.

 

Today I jointed every wire to find that the plastic piece in the rubber bushing has broken so it won't stay together.

 

I reconnected the battery and I can now move the passenger and driver mirrors, lock and unlock the car and open the passenger window but I suspect the motor has burnt out on the driver's door as all the wires are connected. Back to having a partially functioning car until I can get enough money together to take it to somewhere to get the loom replaced and the motor done at the same time.

[UrbanPanzer]

loom is about £85 ish and about 2 hours to fit.

 

 

Edited 7 April, 2020 by UrbanPanzer