Hello all,
Long time viewer, but this is my first time posting. I have recently picked up a 2003 Z4 E85 that initially came to me with a host of general electrical issues which I have worked my way through. The car has clearly had water ingress in the past and this presented the issues:
Alarm / Central Locking / Radio / Windows / Roof / Cluster lights for indicators all not working
Airbag light on
Initially I thought this was potentially an issue with the general module, but after some expert guidance I was pointed in the direction of K-CAN issues. I got access to some better equipment for reading the modules on the bus more precisely and confirmed that there was indeed a K-BUS issue as suggested. I now have access to INPA.
I didn’t go as far as removing all modules from the connector one by one to isolate the cause of the issue as I knew the water had ingresses near the SIM module located behind the handbrake.
I followed guides on this forum and disconnected the module from the car and to my surprise everything on the car now worked, albeit with the presence of an airbag warning light which makes sense as the SIM module was not connected to the car.
I obtained a compatible SIM module and installed it on the car and to my surprise the same issues returned. I had expected that the fix would involve changing the module, coding the new module to the car and finally clearing the errors, but this was now indicating to me that the issue was on the loom / car side.
Sure enough, there was an issue with one of the contacts within the header that plugs into the SIM module and with a few attempts and a fair amount of contact cleaner I got the original module to be plugged in without stomping on the rest of the K-BUS and preventing other modules from talking.
Some observations:
1. For me the critical damage to the pins was on the same side of the header as the side of the car where the leak occurred and many of the pins on the header are unpopulated.
2. If you want to simply test a new module and have a similar fault to mine, you can actually get away with leaving the module in place and removing the latching connector without fully disassembling the console, although any work done to this system should be performed while the battery is disconnected from the car.
3. The Hazard Warning light is an excellent barometer for getting a sniff of if the car is happy. From my experience with my general electrical issues you can be pretty sure the K-BUS is happy if putting the hazard lights on prompts the indicator lights in the dash to illuminate as they should. Not a replacement for diagnostics, but a very assuring thing to see this start working when you are tinkering with a misbehaving K-BUS header and can potentially save you some back and forth.
4. I had initially removed the two fuses associated with the Airbag system and this restored some functionality.
I am now at the point where I can speak to the original module on the network and it even indicates that the system is healthy and that the modules that plug into the SIM are all present and correct.
If I read the status of the safety module in INPA, I am told:
Airbag status: ENABLED
There are some readiness flags, all of which are ticked aside from one:
“System has been switched to sleepmode before”
In addition to this, the current mileage is displayed as: -11080
I think the remaining work to get my airbag light off should only involve a laptop, but I am not certain and thought I would ask the board for some input.
I am blown away with how helpful and friendly folks seem around here and wanted to say thanks for reading my dull post about K-BUS.
All the best,
Ben
Long time viewer, but this is my first time posting. I have recently picked up a 2003 Z4 E85 that initially came to me with a host of general electrical issues which I have worked my way through. The car has clearly had water ingress in the past and this presented the issues:
Alarm / Central Locking / Radio / Windows / Roof / Cluster lights for indicators all not working
Airbag light on
Initially I thought this was potentially an issue with the general module, but after some expert guidance I was pointed in the direction of K-CAN issues. I got access to some better equipment for reading the modules on the bus more precisely and confirmed that there was indeed a K-BUS issue as suggested. I now have access to INPA.
I didn’t go as far as removing all modules from the connector one by one to isolate the cause of the issue as I knew the water had ingresses near the SIM module located behind the handbrake.
I followed guides on this forum and disconnected the module from the car and to my surprise everything on the car now worked, albeit with the presence of an airbag warning light which makes sense as the SIM module was not connected to the car.
I obtained a compatible SIM module and installed it on the car and to my surprise the same issues returned. I had expected that the fix would involve changing the module, coding the new module to the car and finally clearing the errors, but this was now indicating to me that the issue was on the loom / car side.
Sure enough, there was an issue with one of the contacts within the header that plugs into the SIM module and with a few attempts and a fair amount of contact cleaner I got the original module to be plugged in without stomping on the rest of the K-BUS and preventing other modules from talking.
Some observations:
1. For me the critical damage to the pins was on the same side of the header as the side of the car where the leak occurred and many of the pins on the header are unpopulated.
2. If you want to simply test a new module and have a similar fault to mine, you can actually get away with leaving the module in place and removing the latching connector without fully disassembling the console, although any work done to this system should be performed while the battery is disconnected from the car.
3. The Hazard Warning light is an excellent barometer for getting a sniff of if the car is happy. From my experience with my general electrical issues you can be pretty sure the K-BUS is happy if putting the hazard lights on prompts the indicator lights in the dash to illuminate as they should. Not a replacement for diagnostics, but a very assuring thing to see this start working when you are tinkering with a misbehaving K-BUS header and can potentially save you some back and forth.
4. I had initially removed the two fuses associated with the Airbag system and this restored some functionality.
I am now at the point where I can speak to the original module on the network and it even indicates that the system is healthy and that the modules that plug into the SIM are all present and correct.
If I read the status of the safety module in INPA, I am told:
Airbag status: ENABLED
There are some readiness flags, all of which are ticked aside from one:
“System has been switched to sleepmode before”
In addition to this, the current mileage is displayed as: -11080
I think the remaining work to get my airbag light off should only involve a laptop, but I am not certain and thought I would ask the board for some input.
I am blown away with how helpful and friendly folks seem around here and wanted to say thanks for reading my dull post about K-BUS.
All the best,
Ben
Scottish Borders
Attleborough, Norfolk