Best procedure for tracing battery discharge.

[simufly]

I have a battery drain problem.
Battery is in good condition, but will discharge over a couple of days.
No aftermarket mods fitted. No internal/boot/glove box light remains on.
Scan shows CCCU failure to communicate with both front door module (intermittent)
CCCU is 8Z0. 959 433 AF

Rather than a scattergun approach what are the logical next steps to trace this PITA fault?

 

[Dave M]

Does it have a cigarette lighter Simon. It may not be the cause but worth a check.

 

[simufly]

Yes it does but there is nothing plugged into it.

 

[A2-Dork]

are you locking the car ?

 

[simufly]

no

 

[A2-Dork]

as daft as it sounds that could be it

lock it and see what happens

 

[simufly]

ok will give it a whirl, but assuming it works, where is the problem?

 

[PlasticMac]

Power shut down doesn't complete until car is locked, and the CCU knows it's locked, via door micro switches.
You need to fix the door problem, I reckon.
Mac.

 

[simufly]

Well progress, of a sort.
I locked the car on Friday and today it sprang into life so the problem seems to be the car needs to be locked to prevent battery discharge.
Does this point to door module/ lock fault?

 

[PlasticMac]

Well progress, of a sort.
I locked the car on Friday and today it sprang into life so the problem seems to be the car needs to be locked to prevent battery discharge.
Does this point to door module/ lock fault?

The electrics don't fully shut down until the car us locked, and the CCU knows it's locked. Any door/lock related DTCs?
Mac.

 

[simufly]

The electrics don't fully shut down until the car us locked, and the CCU knows it's locked. Any door/lock related DTCs?
Mac.

yes several:
various cant unlock/wont desafe
01330 CM for CC (J393) supply voltage too low intermittent
01331 door control module Drivers side No comms intermittent.
01332 DCM PAX side No comms intermittent.
Clearing them down only the door control modules both sides reappear.
I still have a gut feeling that it is the CCCM thats faulty, its the 433AF model which I think are quite reliable. Perhaps mine is the exception?
WIll try and trouble shoot over the weekend. I will replace the two door modules with the spares I have on the shelf.

 

[PlasticMac]

yes several:
various cant unlock/wont desafe
01330 CM for CC (J393) supply voltage too low intermittent
01331 door control module Drivers side No comms intermittent.
01332 DCM PAX side No comms intermittent.
Clearing them down only the door control modules both sides reappear.
I still have a gut feeling that it is the CCCM thats faulty, its the 433AF model which I think are quite reliable. Perhaps mine is the exception?
WIll try and trouble shoot over the weekend. I will replace the two door modules with the spares I have on the shelf.

If you're any good with a small soldering iron, reflowing the solder joints on the lock pcb is a common fix.
Remember, solder to the iron, not the joint. Let the solder from the iron "wet" the joint.
Mac.

 

[simufly]

The plot thickens: the boot light has not been working for a while. no boot open on DIS either.
Disconnected the battery yesterday, on reconnection both the boot light and DIS worked fine. Sadly not working this morning.
I suspect the cccu is at fault as this is the only common factor with all the odd gremlins in the ele tricks.
How can I stop the car self locking?

 

[audifan]

When you unlock the car open a door that is recognised on the DIS will stop the car relocking.

 

[simufly]

Yep that works, bur here’s the odd thing.
Unlock open all 4 doors. Nothing on DIS.
close all doors
Key in ignition 1position.
open pax rear door internal lights on DIS shows DRIVERS door open! Fuel door not active.
close rear pax all lights extinguish
open front pax door internal lights on DIS shows DRIVERS door open
I think I have a CCCU fault?
Anyone any ideas?

 

[Proghound]

This is a full-DIS car, with the birds-eye outline of the car in vertical rather than horizontal, right? The standard horizontal display uses the 'driver's door' indicator to show that ANY door is open.

 

[simufly]

This is a full-DIS car, with the birds-eye outline of the car in vertical rather than horizontal, right? The standard horizontal display uses the 'driver's door' indicator to show that ANY door is open.

Ah might be having a senior moment. This one is basic DIS. The blue one is full.
Any idea about the lack of boot light/DIS warning?

 

[Proghound]

Ah might be having a senior moment. This one is basic DIS. The blue one is full.
Any idea about the lack of boot light/DIS warning?

I'd suspect a similar bad connection to a microswitch in the boot lock is stopping the car from knowing that it's open.

 

[audifan]

Or blown boot bulb or even boot open too long and light timed out.

 

[simufly]

Or blown boot bulb or even boot open too long and light timed out.

Thanks for the input. Bulb is fine Time out not applicable!
Turns out the micro-switch in the hatch was sticky. Bit of fizz, jobs a goodun.