Xenon Bulb Replacement Problems: Troubleshooting Guide

Merry Christmas to all you diesel mechanics!

After I replaced the xenon bulbs, the low beam headlights stopped working. All the other lights are functioning, but the bi-xenon low beam headlight is shining directly forward (Seat Leon 1P). Here's what I found in the logs:
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein wunderschöner Tag."

"The sun is shining brightly and warmly. The birds are chirping happily in the trees. A gentle breeze is blowing through the grass. It's a beautiful day."
Vehicle type: 1K0
Scan: 01 03 08 09 15 16 17 19 25 37 42 44 46 52 55 56 62 72 77

Vehicle Identification Number (VIN): VSSZZZ1PZ9xxxxxx Mileage: 51,910 km
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein wunderschöner Tag."

"The sun is shining brightly and warmly. The birds are chirping happily in the trees. A gentle breeze is blowing through the grass. It's a beautiful day."
Address 55: Headlight range adjustment. Label file: RKS\5M0-907-357-V2.lbl
Part number SW: 5M0 907 357 C. Hardware: 5M0 907 357 C.
Component: AFS Control Unit 0133
Revision: 00H04000 Serial Number:
Encoding: 2556933
Operating number: WSC 00000 785 00200
VCID: 346CAFC457204E9

Subsystem 1 - Part number: 7L6 941 329 A
Component: AFS-List Module l 0004
Encoding: 00000039

Subsystem 2 - Part number: ID-R missing.
Component: AFS-List Module r.
Encoding: 00000255

5 errors found:
02234 - Headlight module, right side (J668)
004 - No signal/communication - Warning light ON.
Environmental conditions:
Error status: 11100100
Error priority: 6
Error frequency: 16
Lost Count: 194
Mileage: 51819 km
Time: 0.
Date: 2000.00.00
Time: 09:45:14

Environmental conditions:
Voltage: 11.50 V
Speed: 0.0 km/h
ABS 1

01042 - Control unit not coded.
000 - - - Warning light ON.
Environmental conditions:
Error status: 11100000
Error priority: 2
Error frequency: 1.
Lost Count: 191
Time: 0.

Environmental conditions:
invalid
invalid
invalid

02656 - Headlight module, left side (J667), not coded.
000 - - - Warning light ON.
Environmental conditions:
Error status: 11100000
Error priority: 2
Error frequency: 1.
Lost Count: 191
Time: 0.

Environmental conditions:
invalid
invalid
invalid

02657 - Headlight module, right side (J668), not coded.
000 - - - Warning light ON.
Environmental conditions:
Error status: 11100000
Error priority: 2
Error frequency: 1.
Lost Count: 191
Time: 0.

Environmental conditions:
invalid
invalid
invalid

01539 - Headlights not adjusted.
005 - No or incorrect initial setting/adaptation - Warning light ON.
Environmental conditions:
Error status: 11100101
Error priority: 3
Error frequency: 1.
Lost Count: 191
Time: 0.

Environmental conditions:
invalid
invalid
invalid
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein wunderschöner Tag."

"The sun is shining brightly and warmly. The birds are chirping happily in the trees. A gentle breeze is blowing through the grass. It's a beautiful day."

I'm not sure if I'm simply using too much force with the large housings that don't fit properly into the small headlight openings on their backs, or if I inadvertently made a mistake when replacing the bulbs. I couldn't register the headlights because the error codes wouldn't clear. Apparently, there's a missing ID in the right control unit. The right control unit shouldn't be defective, as it was working before the bulb replacement. Perhaps the corresponding ID isn't being transmitted because there was an interruption during the replacement (a contact or cable issue?). Or is it possible that I need to manually enter this ID, which I doubt.

If I re-encode address 55 using the existing values, will this fix the problem, or will it create further issues?

Greetings,
Jörg.

Hello,

Saving the same encoding again shouldn't cause any problems.
Are the "new" load modules properly connected and in good condition? Also, are they the correct ones?

Best regards, Rainer.

The 7L6 941 329 A units tend to fail and leak fluid; I've already replaced several with completely corroded circuit boards.

Quote:

The 7L6 941 329 A sometimes like to flood

.

Code:

Subsystem 1 - Teilenummer: 7L6 941 329    Bauteil: AFS-Lst.-Modul l    X018     Codierung: 00000035    Subsystem 2 - Teilenummer: 7L6 941 330    Bauteil: AFS-Lst.-Modul r    X018     Codierung: 00000035

"also?" or "too?" (depending on the context)

Hello diesel mechanics,

First of all, thank you everyone for the quick feedback!

The light was too yellow for my taste, so I replaced the burners with ones that have a color temperature of 6000K (E1).

My Passat (model years 9-1999 to 11-2012, chassis code 3B5, engine AJM without chip tuning, mileage 382,200 km, first owner, original engine, transmission, clutch, and turbocharger) was recently "taken out" by a reckless driver, so I needed a replacement vehicle quickly. Unfortunately, this replacement car paled in comparison to my Passat...

"Hey Rainer, I haven't made any changes to the control units, neither in terms of hardware nor settings. It was just a replacement of the xenon bulb. I can't see that any connector has come loose in the headlight or that a wire or cable is pinched. To be honest, I still can't definitively say whether a control unit is working or not. Sometimes it's the lack of communication with the control unit, for example, simple factory wiring issues in my Passat, which resulted in the comfort control unit behaving "as if dead," but it could be brought back to life with some new wires. Or, the ABS control unit in my Passat actually failed, and yet it still needed to be "re-coded"."

@ Michael: I couldn't detect any moisture, neither on the headlight lens nor inside the headlight itself. I didn't "touch" the control units. I also find it hard to imagine that they would fail simply because of a bulb replacement – unless I used too much force...

I will perform the coding for the AFS control unit tomorrow using the existing data and will get back to you afterwards. It's probably something very simple, but I can't see it even though it's right in front of me!

Greetings,
Jörg.

Hello diesel mechanics!

Today, I took advantage of a break in the rain to work on my car. I've already replaced the burners with the original ones and then reinstalled the new ones. In both attempts, I was unable to clear the error memory. Unfortunately, it also wasn't possible to recode the AFS control unit.

I'm considering swapping the control units (AFS-Lst.-module) to see if the right one is defective or if there's a "contact problem." However, it seems like I can only do this by removing the headlight assembly, as there probably isn't enough space to remove the control unit from the left side. But now I'm starting to think that's too much trouble again...

Does anyone have a better suggestion?

Greetings,
Jörg.