Strange electrical behavior but only when the car is running

[11fbwd]

Let’s play a game...diagnose the electrical problem online! 2006 E85 Z4 3.0si w/95k miles.

These symptoms only present themselves when the car is running. When the key is turned to accessory power, everything works normally (none of the symptoms below present themselves).

Symptoms:
-On the instrument cluster: Turn signals don’t turn on at all, turn on with delay, or stay on after a mechanical cancel; outside signal lights work as they should and follow the stalk. Same with fog lamp indicator (delayed illumination with fogs turned on/turned off). Also, airbag light turns on and off, but not in any pattern. These do not seem to be affected by bumps or passenger in passenger seat. Finally, cluster also dims/brightens without input from me when the headlights are on.
-On the radio: volume knob is non-responsive for controlling volume but will power radio on and off. Steering wheel volume control does not work. If radio is on, there may be volume spikes without input (maximum volume-silent-maximum volume). Time shown on radio display is dragging behind the time shown on instrument cluster but then “catches up” as I’m driving. However, bluetooth phone calls work fine and volume can be adjusted normally.
-Autodim mirror and driver’s side view mirror are in maximum dim position when lights are on.
-Dash light dimmer controls all interior lights normally but cluster is not responsive.
-Everything else electrical (windows, top, lights) works normally.

Based on my research I’ve identified the following possibilities:
-Alternator or voltage regulator (believe original)
-Battery (current one is two years old)
-Faulty radio or cluster
-Faulty hazard switch

Anyone have any ideas? Want to avoid throwing parts at it if possible.

[RossBMWZseries]

These are he same symptoms I’ve been having for months and have had no luck figuring it out. Typically the symptoms happen when the airbag symbol lights up on dash. I’ve read it could be different things, from the airbag module to the SAS to the clockspring to the ignition switch. I haven’t figured it out and the problems are more consistent now, specially on a really hot day. Even the top doesn’t latch/unlatch when airbag light is on. Sometimes the trunk won’t open either. It’s not the GM5, Scott checked it out so that’s ruled out. Let me know if you find something and I’ll do the same. I’m about to replace my ignition switch again, only because it’s cheap and the last time I replaced it, it was with a used one I bought. Perhaps that ruined things and now is giving me these symptoms. Here’s an article from pelican where it talks about it;

https://www.pelicanparts.com/techart...eplacement.htm

[Steeler]

Yep, most of these issues are present with my 3.0

I have a used cluster incoming to rule out that.
GM5 is good. New ignition switch installed.
There are 4 things that create the loop for the body.

Cluster
Ignition switch
LMZ...Light switch module
GM5

Also frayed wires to ground is a definite possibility.

[RossBMWZseries]

Originally Posted by dbarton62

Yep, most of these issues are present with my 3.0

I have a used cluster incoming to rule out that.
GM5 is good. New ignition switch installed.
There are 4 things that create the loop for the body.

Cluster
Ignition switch
LMZ...Light switch module
GM5

Also frayed wires to ground is a definite possibility.

You bought the entire cluster? used or new?
Have you checked for any codes? I'll post the codes my car is throwing. I did post them on the thread i started months ago but it got complicated for my understanding.

[Steeler]

Originally Posted by RossBMWZseries

You bought the entire cluster? used or new?
Have you checked for any codes? I'll post the codes my car is throwing. I did post them on the thread i started months ago but it got complicated for my understanding.

I had my car into the indy and he could not connect to the car because his program could not locate terminal 15. Good explanation here.

Hence the ignition switch got replaced to no avail............So we could not check codes on the body modules.

That is when we got into the architecture of how the body electrics work.

If the cluster does not solve my issues I will be getting a used HU and so on.
I hope I do not have to go digging to find a frayed wire behind the dash.

[dc_wright]

Troubleshooting issues with the digital communications busses in the Z4 can be pretty challenging. All it takes is one module on a given bus to have an issue and hang the bus and the data to ALL the modules and instruments on that bus either stops or gets corrupted. The diagrams on page 18 of this BMW diagnostics training manual will give you and idea of how things are connected.

[11fbwd]

Thanks for all the helpful replies.

Someone else suggested he had the same symptoms with the steering angle sensor hanging up, and he had to have his dealer re-program his SAS to solve the problem.

At this point I'm going to start with the easy stuff - going to have AutoZone test the alternator to make sure I'm not over/under voltage, and make sure there's nothing weird going on with the battery.

[dc_wright]

Originally Posted by 11fbwd

Thanks for all the helpful replies.

Someone else suggested he had the same symptoms with the steering angle sensor hanging up, and he had to have his dealer re-program his SAS to solve the problem.

At this point I'm going to start with the easy stuff - going to have AutoZone test the alternator to make sure I'm not over/under voltage, and make sure there's nothing weird going on with the battery.

I believe that was me where my SAS hung and reprogramming it fixed the problem. Essentially anything on the I or K buss that hangs can cause the same issues.

[RossBMWZseries]

Originally Posted by dc_wright

I believe that was me where my SAS hung and reprogramming it fixed the problem. Essentially anything on the I or K buss that hangs can cause the same issues.

This is all great intel guys. Dc_wright, how can the SAS be reprogrammed? I tried it with my Foxwell NT510, not sure if I did it correctly though. I did clear the codes and the car seems to be running perfect now. However, every time I clear the codes, the car runs fine for a while and a few weeks later the same problems come back.

[dc_wright]

Originally Posted by RossBMWZseries

This is all great intel guys. Dc_wright, how can the SAS be reprogrammed? I tried it with my Foxwell NT510, not sure if I did it correctly though. I did clear the codes and the car seems to be running perfect now. However, every time I clear the codes, the car runs fine for a while and a few weeks later the same problems come back.

To reprogram it you are reloading the firmware stored in it's memory that controls it's operation. You need the firmware file and a software utility to do the load. It's not something a code scanner will do.

[sclui56]

I have my 08 coupe at the indy for service + window regulator. I mentioned the issues I have with the turn signal/air bag lights + intermittent radio issue. He suspected it may be the bad contacts in the switch unit slip ring, what do you guys think??

http://www.realoem.com/bmw/enUS/show...19#61318379091

Update - I failed to mention that the vehicle does not have any fault code, so it is more like a glitch in the electronics.

[Ascanio]

So? What was the problem?
I am going through similar issues. Would love suggestions

[Gustavosan96]

Originally Posted by Ascanio

So? What was the problem?
I am going through similar issues. Would love suggestions

Ok so basically this was happening to my 2003 Z4. Check this airbag module that's hidden under the arm rest. One of the pins had corroded and broken off, so it wasn't completing the circuit throwing all sorts of electrical issues including the turn signals not showing up on the dash. Fixed it by sticking a piece of soldering wire inside the harness that connects to it, where the missing pin is supposed to go, to act as a new pin. When you go to secure the harness it makes contact and worked for me. Cleared all my electrical issues and didn't have to buy a new module