Error code 55C3 (VTG: AWD limp-home control activated. No DSC specified nominal torq)

[James7878]

Hi all,

What does the 0055C3 error code mean? In my case, I get "DBC failure" and "4x4 system and DSC failure" and this is the ONLY code ISTA+ reads. Surfing the web suggest that usually this error is accompanied by other errors but in my case, I have no other failure.

More Details
Within the last few weeks, I've got "DBC failure" and "4x4 system and DSC failure" with few dash warning lights on. In all cases, it happened when cruising normally. Using INPA I read the errors and this is what I got every time. NOTE: Errors cleared after each reading.

1st time - Early Nov 2020
00E205 PDC: K-CAN-High wire fault
0055C3 VTG: AWD limp-home control activated. No DSC specified nominal torque.
005E63 DSC: Brake light switch permanently actuated

2nd time - Late Nov 2020
00E205 PDC: K-CAN-High wire fault005E63 DSC: Brake light switch permanently actuated
0055C3 VTG: AWD limp-home control activated. No DSC specified nominal torque

3rd time - 2 Dec 2020
0055C3 VTG: AWD limp-home control activated. No DSC specified nominal torque

4th time - 8 Dec 2020 (UPDATE: ADDED)
0055C3 VTG: AWD limp-home control activated. No DSC specified nominal torque. (Mileage: 143976km)
005E63 DSC: Brake light switch permanently actuated (Mileage: 143976km - same as above)

Seems like the main error is 55C3 but I couldn't find what it truly means.

Any thoughts?

[shogun]

Moved from X general to X5 forum

[James7878]

Thanks. I originally posted in X because I assumed it's AWD related issue not limited to E70.

[jclausen]

I would start with the brake light switch

[James7878]

Thanks. Even though last time it happened without brake light error?

[James7878]

It happened again today. This time, two error. Updated original post with new information.
jclausen, you may have a point. Apparently the brake error happens exactly at the same time. I paste more ISTA+ details below (screenshot):
0055C3 VTG: AWD limp-home control activated. No DSC specified nominal torque.
Attachment 682065

005E63 DSC: Brake light switch permanently actuated
Attachment 682066

[James7878]

FIXED - Read on for more details
Despite KMs and time in ISTA+ not guiding well in this case the root cause is the following code:
005E63 DSC: Brake light switch permanently actuated

Following picture is the brake switch. They are adjustable so that the far end (left side of the pic) just meets brake pedal. When brake pedal is depressed it travels away from this switch and this is how it detects the brake pedal is applied. The switch is adjustable for installation; meaning, you leave it far open and then release brake pedal to spring back to its natural position. In doing so the switch compresses in just enough. So theoretically it's possible to somehow press the switch further in (compress too much) which results in confusing the switch thinking brake pedal is permanently applied. That was my issue! Somehow there was 2mm gap between brake pedal and the switch. My best guess is that last year I replace brake booster and perhaps during installation somehow this switch was pressed in more than it should. It now works fine. Time to fix? 5 mins.

It makes sense why car thinking brake is applied permanently confuses both multiple other modules in the car. I don't understand why ISTA+ didn't show sequence of errors in natural way to suggest brake issues is causing everything else. For now I call this FIXED but I'll report back if I find anything more hoping to help someone else someday.