[Solved] 2003 e85 k bus - roof/airbag light/instrument cluster errors

D

Dwr2025

Member
Hello,

I'm having some troublesome electrical issues that all seem to point to the k bus or something attached to it. The airbag light is on, and whilst the car runs etc various electrical systems aren't working (roof, no indicator lights on instrument cluster etc).

Having run diagnostics with INPA there are communication errors with the majority of modules but it does return the following errors:

---------------------------------------------
RESULT: 3 errors in memory !
---------------------------------------------

K bus

error frequency : 45

Short circuit to batt
error present
---------------------------------------------
light module-EEPROM error

Error frequency : 45

Open circuit
Error present
----------------------------------------------
Airbag

Error frequency : 40

Error present
K-Bus telegram70h failed (Mask 10)
---------------------------------------------

I spotted that someone else had traced these back to missing fuse 45, but I've checked and replaced this (even though it looked ok). I think disconnected the central airbag module (errors persisted with this disconnected), cleaned the connections and reconnected it but without any effect.

Most recently I pulled out the connector bus and disconnected each cable, one at a time (disconnecting the battery, the re-running the error scan/clearing errors each time), but with no improvement.

The only thing I can think of, is that there's some kind of break in the circuit which is having the same effect as pulling fuse 45 but I've no idea how to proceed with troubleshooting from here.

Does anyone have any suggestions, there aren't any specialist garages near me, so if I can't get it sorted the car will be one it's way to the scrapy!

Many thanks!
 
What condition is your central airbag module in?

Check for water ingress and damage to the plug? If you unplug it do the comms errors disappear?
 
Module looks fine, no obvious corrosion, I gave the connectors a clean with contact cleaner as I'd seen other people report this as causing similar issues. I get the same errors/problems with the central airbag module completely disconnected.
 
What I’d do next if I was in your position

Step 1- unplug each module in the car to see if one of them is causing issues. Use inpa to get a full list and do them one by one

Step 2- get to the k-bus consolidation point under the passenger side fuse panel area and look for damage

Step 3- check all 7 earth points and wiring
 
Ah and of course…

Check for aftermarket stuff that may be causing issues like Bluetooth devices or head units
 
bigwinn said:
What I’d do next if I was in your position

Step 1- unplug each module in the car to see if one of them is causing issues. Use inpa to get a full list and do them one by one

Step 2- get to the k-bus consolidation point under the passenger side fuse panel area and look for damage

Step 3- check all 7 earth points and wiring
Click to expand...
Would you manually unplug each module at the directly at the module, rather than just at the k-bus consolidation points behind the fuse panel (I've done that already and there was no obvious damage/corrosion).

Good shout about the aftermarket stuff, there is an aftermarket stereo, although it's one of the things that's still working.

Thanks!
 
Only thing I'd add is to keep disconnecting stuff till the K-BUS comes back online. Dont just do one at a time as you could have multiple failures.
Speed hack: put an indicator on. If the k-bus comes back you'll see and hear them again on the dash. Saves scanning every time.
I've had a BTooth connector take the whole car down. Laughed about it eventually :rolleyes:
 
Street said:
Only thing I'd add is to keep disconnecting stuff till the K-BUS comes back online. Dont just do one at a time as you could have multiple failures.
Speed hack: put an indicator on. If the k-bus comes back you'll see and hear them again on the dash. Saves scanning every time.
I've had a BTooth connector take the whole car down. Laughed about it eventually :rolleyes:
Click to expand...
I've disconnected everything in the k-bus breaker and directly disconnected the aftermarket stereo but no improvement, guess I need to pull the modules one by one directly and see if I can identify the failure.. Thanks!
 
I think I saw ‘short to positive’ on your diags. I’d guess that’s more likely in a unit than a broken wire but anything’s possible. I’ve got my fingers crossed for you 👍🏻
 
You must log in or register to reply here.
Back
Top Bottom