LIN bus error on climate panel?

WilliamG17 · 05-05-2024, 08:32 AM

Hello!

I have a really hard to find fault in my 2006 E91 330xd.
All 8 heater flaps are sending LIN bus errors and I cant seem to get rid of any.

I have tried measuring on the connector going out of the IHKA to the flaps. No continuity to grund on the bus line or the 12V+ line. I also disconnected the last heater flap connector and measured the bus line from IHKA (7 flaps connected in series) which gave me about 8 ohms. No open loop.

I also tried swapping 2 motors just to try and isolate any unmeasurable error, but to no avail. At this point I was certain it should be the IHKA thats faulty. But I have tried 3 different climate panels now and one of them was borrowed from a working car.

Still 8 heater flap LIN bus errors no matter what. Should I be looking at the "input" end of the IHKA? Can the junction box kill the LIN signal somehow?
Just to clarify, the blower motor works and the panel buttons/lights work as expected.

Some help in how to proceed troubleshooting would be really appreciated.

WilliamG17 · 05-09-2024, 10:43 AM

I assume this is no ordinary fault since I can't find any info on it. Is it possible to run the IHKA "standalone" without the incoming CAN lines? Powering the IHKA from a separate voltage source but keeping the outgoing LIN bus connector connected?

To clarify, I bought the car like this and cannot know what events might have caused this. Is it possible that previous owners have jump started the car forcefully causing electronics to take damage?

Seeing as I have nothing to go on I might need to start randomly swapping parts. Would my best bet be to swap the junction box first?

WilliamG17 · 05-12-2024, 11:36 AM

Did some more troubleshooting today.

Tried swapping some other flap motors for the defrost motor (1st one in lin bus) but no change. However I did find out that some motors would "syncronize" when I plugged them in, and some didn't. Even though it was on the same connector. By syncronize I mean that they spin the motor continously when plugged in.

I also did some measuring at first flap motor connector (with ignition on, IHKA working):

+12v on motor supply pin
120 ohms to chassis ground on ground pin
+1.3v at incoming LIN bus line

The 1.3 volts is constant, no change if I press any buttons or anything, doesn't fluctuate or anything. If I disconnect the connector at the back of climate panel I get 0 volts on bus line. From what I've read it should work between like 1 to 12 volts, so I would expect some variance in the voltage at least.

Well this didn't really get me any further. Either I replace all the motors or the junction box at this point?

05-05-2024, 08:32 AM	#1
WilliamG17 Registered 0 Rep 3 Posts Drives: BMW 330xd Join Date: May 2024 Location: Sweden iTrader: (0)	LIN bus error on climate panel? Hello! I have a really hard to find fault in my 2006 E91 330xd. All 8 heater flaps are sending LIN bus errors and I cant seem to get rid of any. I have tried measuring on the connector going out of the IHKA to the flaps. No continuity to grund on the bus line or the 12V+ line. I also disconnected the last heater flap connector and measured the bus line from IHKA (7 flaps connected in series) which gave me about 8 ohms. No open loop. I also tried swapping 2 motors just to try and isolate any unmeasurable error, but to no avail. At this point I was certain it should be the IHKA thats faulty. But I have tried 3 different climate panels now and one of them was borrowed from a working car. Still 8 heater flap LIN bus errors no matter what. Should I be looking at the "input" end of the IHKA? Can the junction box kill the LIN signal somehow? Just to clarify, the blower motor works and the panel buttons/lights work as expected. Some help in how to proceed troubleshooting would be really appreciated.
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05-09-2024, 10:43 AM	#2
WilliamG17 Registered 0 Rep 3 Posts Drives: BMW 330xd Join Date: May 2024 Location: Sweden iTrader: (0)	I assume this is no ordinary fault since I can't find any info on it. Is it possible to run the IHKA "standalone" without the incoming CAN lines? Powering the IHKA from a separate voltage source but keeping the outgoing LIN bus connector connected? To clarify, I bought the car like this and cannot know what events might have caused this. Is it possible that previous owners have jump started the car forcefully causing electronics to take damage? Seeing as I have nothing to go on I might need to start randomly swapping parts. Would my best bet be to swap the junction box first?
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05-12-2024, 11:36 AM	#3
WilliamG17 Registered 0 Rep 3 Posts Drives: BMW 330xd Join Date: May 2024 Location: Sweden iTrader: (0)	Did some more troubleshooting today. Tried swapping some other flap motors for the defrost motor (1st one in lin bus) but no change. However I did find out that some motors would "syncronize" when I plugged them in, and some didn't. Even though it was on the same connector. By syncronize I mean that they spin the motor continously when plugged in. I also did some measuring at first flap motor connector (with ignition on, IHKA working): +12v on motor supply pin 120 ohms to chassis ground on ground pin +1.3v at incoming LIN bus line The 1.3 volts is constant, no change if I press any buttons or anything, doesn't fluctuate or anything. If I disconnect the connector at the back of climate panel I get 0 volts on bus line. From what I've read it should work between like 1 to 12 volts, so I would expect some variance in the voltage at least. Well this didn't really get me any further. Either I replace all the motors or the junction box at this point?
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