Restraint and Control System faults

[Dr Stig 2]

Hi Guys,
I've been gone a while. Hope you were not getting in too much trouble while I was gone.
I've been lost in work for a few years, but now at home again and finally getting to drive my Z4 again.

Interesting problem has arisen - and I was wondering if anyone else has had it happen to them.

Out of the blue my car came up with a raft of errors when I tried to start it.
Restraint system faults, Control Systems Faults. Warnings that the ABS, Airbag, park brake would not work.
The speedo stays on zero.
The BAS is not operating.
The park brake wont work.
AND THE WIPERS GO CONSTANTLY AT ONE SPEED!

I left it locked for three hours, then the problem went away the next time I started it.

A few weeks later, starting it after a lunch out, all the same symptoms. Left if for an hour, but they didn't go away, so I drove (feeling embarrassed with the wipers going) to the local dealer.
They looked at it for a few hours, then advised me that there was some wear and corrosion to some wires, which they replaced and heat shielded, but apart from that it tested ok. Away we go, not too heavy a repair bill.

BUGGER.
Next time I went to drive the car, all the same errors.
This time it is not going away.

Looking at a few threads on other forums with N54s, it has been suggested it is a battery voltage, an alternator failure, and a control unit / computer programming error.

Has anyone had any first hand experience with this kind of error?
The dealer is stumped.

Regards
AM

[Lurcher]

How about a full shutdown/reboot? Pull battery cables, attach them together (to drain residual) and leave alone for an hour or so.

Used to do this on the e38s so you know you are starting from scratch troubleshooting.

Does sound like a battery voltage issue. I would try the above first, if that does not help - try again but hooking back up with a charger attached before you try to start...

I've never heard of it in these models, but again in the e38 we would have some of these issues with a bad ignition switch ($35 part)

Keep us updated...

[Gunzaro]

Welcome back Stig. I think with the age of the vehicle especially if it hasnt been driven regularly or a trickle charger used then it could well be the battery.

[Dr Stig 2]

They gave me the car back, to test it for the next few weeks.

No issues with anything while on the test machines.
Faults when you start it off the test machine.

They reprogrammed the control system computers, and tested the alternator and battery.
Working atm, so it has com home for an extended road test to see if it was just a software glitch.

[BBriner]

Hi.

I am curious if the issues you were having came back or not.

I am also having some weird electrical problems with my 2009 Z4.

http://www.e90post.com/forums/showthread.php?t=1093644

[jparnes1]

Good to see you again Stig. Lurcher's advice about draining the system by touching the 2 battery cables together often resolves electrical issues. I'd try that first.