1996 850 - trip computer issue

Teddy1975 · Post by **Teddy1975** » 14 May 2016, 15:28

I replaced the timing belt along with rollers and water pump Friday, and when I started the engine everything seemed ok. Then, when I drove the car home from my parents I noticed the trip computer display was completely blank.

I know it worked before the TB job and I want to think that it is unrelated to that repair. The only thing I did that would/should have made any impact on the electrics was to disconnect the negative lead on the battery before I started working on the TB and reconnecting it after the job was done.

Another issue is the cabin light will just shut off upon closing the doors, instead of waiting for the ignition to be turned or 30 seconds delay as it used to do. The cabin light isn't a big deal, I just find it strange that these two faults occured right after swapping the TB. In my humble opinion none of these things should be related at all. Am I mistaken?

I glanced over the fuses and all of them seem fine. The gauges and mechanical odometer works, as does the backlight of the instrument panel, including that of the trip computer. The only outstanding issue in terms of electrical problems is a loud whine from the generator bearings, the generator output is fine though.

I really appreciate any and all help I can get.

Thanks,
Teddy

Post by **erikv11** » 14 May 2016, 16:56

I agree, the symptoms are not likely related to the TB job.

I don;t have any great ideas on this one. Simply because the two electrical issues seem so unrelated, I would check the electrical portion of the ignition switch. Try jiggling the key, see if the trip computer will come back.

Post by **BEJinFbk** » 15 May 2016, 00:35

You could have inadvertently shorted something
while working and blown a fuse - It happens...

If the ignition switch proves out as OK, it may
be worth taking a minute with a meter to check
all of the fuses in the box. It's quick and easy.

With the key on, run through the entire fuse box and check for
voltage at both ends of each fuse. Use the little metal nubs on top.

You'll probably run across a few with no voltage at either end
( some only see power when the accessory that they protect
is actually in use ) and that's OK. But if you hit a fuse that's
live at one end and has no voltage at the other, you've found
a blown fuse. Hopefully, just replacing it will fix you up.

Teddy1975 · Post by **Teddy1975** » 15 May 2016, 09:04

I'll try testing the fuses and the ignition switch when the weather shows itself from a nicer side than today. It is more of a nuisance than anything else, I just prefer everything to be in working order. Maybe not mint condition, but at least working

Thanks for the ideas guys.

Teddy1975 · Post by **Teddy1975** » 17 May 2016, 12:14

All fuses checked out ok.

Figured I'd try to reset the computer and everything else by removing the negative lead and leaving it off for a few minutes. When I put it back and got behind the wheel to test, a solid 12:00 was present in the trip computer display and a short test drive later I can say that everything works as it is supposed to.

Post by **Clemens** » 17 May 2016, 15:36

That's great to hear. Good to know how helpful a reset can be.