The Gremlins have attacked- Any Help Appreciated

[Ken Mauldin]

I am New to the forum. I hope this is appropriate, If not please instruct.
I have had my Z4 for a year now and have had a great time with only simple problems until only recently. It began about 3 weeks ago with a flicker of the passenger airbag light on the console…then it began to stay on for a while…a week later the airbag failure light in the cluster came on and has stayed.
1.The passenger airbag light may come and go but the cluster light is there even when key is only in the “unlock steering wheel position” and sometimes just flickers and the odometer flickers with it.
2. Since this occurrence the seatbelt indicator light is out… buckled or not….no gong…nothing…. not even on the cluster on “precheck”.
I have a small code checker and only codes I find and consistently show are “9408 undervoltage during self test” and “93D0 Undervoltage “these are in the airbag system check. The data stream here lists the seat belt latches as not buckled (even if they are) .Passenger airbag ON (even when light is lit) and Passenger occupancy “not assigned”.
Local mechanics find nothing more than these two codes and I head to the other side of the Island for “THE DEALERSHIP”. I decide to give it a quick wash before I leave and….
3. When I turn on the wipers they go berserk stuttering and stopping and chattering….can’t find home…just as if the power is stuttering. What the *&%$... turn them off and head for help. On the way over it gets a bit chilly so I turn my seat heater on and my wife follows suit….
4. and the seat heaters shut down….
The Dealer tech spent most of the day exploring the situation….he found only the same two codes listed above, but did verify that the airbag module supply was not undervoltage and the Battery was good 12.76 V and 790CCA. He also said that the wiper motor was bad and they suggested replacing the airbag module and the wiper assembly for $3000 and change.
The charge for the diagnostic was a bit more than I had expected for a bit less than I had hoped for. It was late so we headed home. On turning on the driving lights we found…
5. the auto dimming of the dome and well lighting failed to do so. We drove with the inside lights continuously brightening and dimming for the hour and half home.
Addition info is that the airbag lights, the seat heaters, the interior lights are all sensitive to… maybe RPM…maybe alternator output. The airbag lights will begin to flicker as well as the odometer readings with the key in the wheel unlock position (note the odometer should not be displaying) at a low idle. If the switch is turned to “ run” they turn hard on. The seat heaters will operate at idle but turn off when rpm is increased.
My belief is that something has gone to ground or something is not grounded properly. But what do all these system have in common.
I have order a used airbag module and hope I can find someone to program it and have a dream that this whole nightmare will disappear.
I have had a wonderful year in Hawaii driving this fine machine and it breaks my heart that this is how it is ending
Any Ideas and suggestions would be appreciated. Sorry for the novel.

[Ken Mauldin]

A bit more found today. Verified that the wiper supply voltage is dropping in and out on both slow and fast speed.
This voltage "chatter" is shown also on the dome lights and on position 1 on the Ignition switch.
I had a difficult time resetting the service interval today due to it.
Come on somebodies surely has some idea.

[Muzz258]

I would be looking for a common point of failure. Something like a loose/dirty earth connection to the engine or body work. Alternatively a loose connection in in the positive supply system.

Your battery checked out OK. Did they also check the alternator? You should have around 14V at the battery with the engine running if you have a good alternator.

[Ken Mauldin]

Thanks, I am surprised that they didn't check the alternator. thanks for your suggestions I have been crawling all over it looking for grounds, pulling apart every connection I can find and spraying with cleaner wire brushing. I opened the main module area and under hood fuse block unplugged cleaned and repluged.
NO effect. Every thing I look at, looks brand new. Shiny brite not even dust. Tomorrow I am pulling the console and removing the airbag module. I so hope the contacts have some corrosion...but I bet they are shiny brite.
Thanks for the conversation.
I have actually sold this car to be delivered in 3 weeks.....I hate telling her she can't have it. I may have to take it back to the mainland with me.

[Ken Mauldin]

PROBLEMS SOLVED.....A Great Tech at "Kona European Auto Repair" Checked fuses found several showing low voltage....traced back to 1 leg of the ignition switch.
Replaced switch .....YEA everything is back to normal.
Asked BMW for a refund of their $350.00 miss-diagnosis.....We will see.

[Ken Mauldin]

I was very impressed with the way BMW-Kona-Hawaii handled the situation. They owned up to the miss-diagnosis and immediately gave me a total refund. It was an embarrassing situation for them and the service manager said that the service dept will have a "meeting" about it and discuss how to insure that jobs get routed to the appropriate tech.