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Discussion Starter #1
Hi All,

This is my first post so let me know if I go wrong anywhere and id appreciate any help.
This weekend I went at my car to try and resolve the water leaking into the front of the car. To resolve this I removed the inner door panels and put a load of silicone on them and did the same will the pollen filter.
While I had the door card off I decided to inspect the drivers door wiring harness as no electronics worked on the drivers door at all and it also wouldn't unlock with the fob, all other doors do.
I repaired two large wires in the harness, both the largest wires in the loom, a large brown one and a large red with a white line, which had sliced through the insulation and I assume were shorting on the doors metalwork.
Upon reassembling the door I now have some functionality back. The central locking buttons on the drivers door now works but only functions for the drivers door, the drivers door window can be opened and closed by its switch but none of the other three window switches open their corresponding windows, all open with the switch on the doors, and the door lock still doesn't function with the fob. when I put the key in the drivers door an attempt to open or close all windows only the drivers door responds, power mirrors and boot/trunk popper also don't work
Essentially the drivers door doesn't seem to be communicating with the rest of the car.
I have checked the CCM and it is dry within the plug and box and the circuit board etc looks fine. outside of the box the wiring is wet but I cant immediately see any signs of any corrosion on any wires.
I checked all microswitches in the drivers door lock assembly while I had it open and all are fine.

Could it be that I need to clear codes in the OBD now that I have repaired the damaged wires in the drivers door?
I find it difficult to see that the window switches have become faulty as the fuel filler cap etc also aren't working.
I figure the wiring goes behind the dashboard to the CCM and then the signals are distributed from there?

a little side note.... what is the key hole (next to boot popper and fuel filler button) on the drivers door supposed to do?

again, I'd appreciate any help you guys could offer, I'm sure someone has had this very some fault, it seems B5's all have the same faults..

Regards.
 

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Most likely is that the CAN lines (the smallest twisted-pair wires in the door harness) are broken. In this case, the driver's door will work as a 'standalone control unit', bot can't 'talk' to the CCM, nor the other three doors.
Same for the gas door - most likely, its wire is broken (gas door, while included in the scope of body electronics, isn't controlled by the CCM.) Or the lock actuator failed.

The lock cylinder on the door panel (next to the trunk button) is the 'valet' switch - it locks-out the trunk release controls (all of them.) Idea is that you lock the trunk w/ a master or flip key, and then hand the parking attendant (valet) the valet key (which does not fit into that cylinder, nor the glovebox or trunk cylinders. Only fits into doors & ignition.)
 

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Discussion Starter #3
Ok, I guess these wires come from the window motor control box, any idea of the colours of these wires? I did do a continuity check and all wires which went through the door bend and all seemed good. I even had a play with the wires while I was at it to make sure it wasn't intermittent. Could it be from the CMM to the drivers side door connector I wonder, rather than from inside the door to their connection in the drivers footwell?

Thanks for your reply
 

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The Comfort-CAN lines are Orange/Lilac (CAN-High), and Orange/Brown (CAN-Low.)
NOTE: CAN-High is Or/Li only in the body harness - at each door connector (at the pillar connector stations), it becomes Orange/Green (in each door harness.)

If the breaks are in the body harness, it would be between the CAN splices (which are near the CCM, in the floor wiring) and the door connector. At that splice is where all of the door CAN lines are, well, spliced together - only one pair goes to the CCM, not five pair. ;)

I'd check the door harness again. While corroded CAN splices in the body harness aren't unheard of, broken wires are quite rare. Broken wiring in the door harness, particularly within the flexible boot, are not uncommon.
 

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Does the 3B3 have CAN on the doors? I thought that started with the 3BG (B5.5).
 

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Crap, just noticed that - or, maybe a typo on OP's part?
B5 = 3B; B5.5 = 3BG.

3B does have CAN to the doors - it's a 'low-speed' CAN (not the 'high-speed' CAN of 3BG.) And, the colors may be different - I don't have my Bentley at hand; those wire colors were out of a PDF that I have of 3BG body electronics (from ELSA.)
 

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That's 3BG, good sir. ;)

Yours is definitely acting like the driver's door module (the window motor) has no CAN connection. I'd (again) suggest that you re-check those CAN lines.
 

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Discussion Starter #9
You'd know better than I :) I'll get at it in the next couple of days and check the continuity all the way from the door window motor to the CCM! Thanks for the help guys!
 

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Discussion Starter #10
A quick Google (serious danger of misinformation) has indicated to me that the 3B3 is the saloon (sedan) and the 3BG is the estate (wagon). Ring true to you guys?
 

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For the US, it was either B5 or B5.5 with no distinction as to body type.
 

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Discussion Starter #12 (Edited)
So.... I had a good look at the Canbus lines today from the drivers door motor to the CCM. I found the splices everyone says corrode and they were just that, although I think I might have broken them off during unwrapping them. If anyone can't find them cut the cable tie (zip tie) off the rubber boot which goes into the CCM outer box and slide it out of the way, they're under there.
20200118_141457.jpg
Unfortunately upon reassembly with the corroded areas removed and soldered in a new piece of wire there was no difference... still no function from the drivers door. I then did a continuity check on the wires all the way from the door window motor connector to the connector on the CCM and both wires check out just fine. Is there a chance that I now need to clear the OBD codes before it will become functional? Quite frustrated. I can on my hope that this got me one step closer. any ideas? Thanks.
 

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Discussion Starter #13
UPDATE
I have largely resolved my issues :D
I went to a breakers yard and got a replacement circuit board which is within the drivers door control module, I was doubtful at first because it didn't look the same as the one coming off, same fitment etc just a different component layout. Plugged it in and I now have all functions back and working except the fuel filler cap release?
I think someone might have replaced the whole door control module in the past for the wrong one because although the boards looked different the part number on the inner door card assembly was identical.
 

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The fuel filler release is an odd exception. It's totally hardwired; the door control module has nothing to do with it.

Fuel filler power is from fuse 14, red/blue wire to 10-position grey connector to door. Goes to switch on door; switched side comes back to same connector as red/green. Wire proceeds from there to the fuel filler door motor.

The red/blue wire is spliced in the floor harness; it also powers the CCM, so you've probably laid hands on it!

The switch only works if it's "unlocked." The lock beside it prevents it from closing the contact if "locked."
 

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I'd check the fuel filler door switch first. I've seen a few go bad as it's easy to get them wet if the window is down during a rain, etc. They can be opened and cleaned pretty easily so it's a good thing to check first.
 

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Discussion Starter #16
I think it actually works although the right parameters have to be met for it to work....I.e. engine off but ignition on, also the drivers door might have to be closed? It seems to work sometimes but not others. Anyhow I'm pretty happy with the results so I think this thread is complete.
Massive thanks to all who provided information, I hope someone in the future finds good use for this information too.
 

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I have to say that sounds like a flaky switch to me. I've popped my gas door while driving, while the door is open or closed. It always just works. A switch that works sometimes and not others sounds like a switch that is on its way out. Just FYI but hopefully it won't leave you stranded at a petrol station with the gauge on E.
 
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