Instrument Cluster Resetting On Ignition

[johnsnow]

Tried 2 new batteries an S3 and S5 Bosh and still having the same problems.

2 out of 3 times when I start the car the instrument cluster effectively resets. It goes dark for a split second then flashes back on with the clock reset.

When it doesnt reset (the 1 out of 3 times) when I start the car the cluster dims massively for a split second while the car tries to start

Any ideas what this could be? Starter Motor? Alternator?

[Loren]

You will likely need to have your OPC put a PIWIS tester on the car and also re-program the cluster.

[johnsnow]

You will likely need to have your OPC put a PIWIS tester on the car and also re-program the cluster.

out of interest why would the cluster need re-progamming - the cluster seems fine once the car has started (the problem is just a momentary restart lasting a fraction of a second immediately after the engine has started)

Edited July 14, 2012 by johnsnow

[Loren]

Because 9x7 series cars are known to have had some software glitches. Re-programming automatically updates the software/firmware to the latest versions.

[wvicary]

I would also verify the chassis grounds.

[johnsnow]

I would also verify the chassis grounds.

Thanks how would you verify a ground? The cables seem to be attached fine

[wvicary]

You can remove them and clean the contact surface but sometimes the fault is within the cable itself. I use a set of jumper/booster cable to provide a substitute ground path from engine to chassis and retest to see what effect it had on the fault.

[johnsnow]

You can remove them and clean the contact surface but sometimes the fault is within the cable itself. I use a set of jumper/booster cable to provide a substitute ground path from engine to chassis and retest to see what effect it had on the fault.

Great idea I tried this first with the front ground (but had the same result) I then opened the engine bay but I couldnt for the life of me find the engine ground pictured here is there 987 location different?

[RFM]

johnsnow, the engine to chassis ground cable is located underneath the engine.

[johnsnow]

johnsnow, the engine to chassis ground cable is located underneath the engine.

Thanks, running the battery with a multimeter it records a steady 12.8v even with heaters etc. on seems something is draining it would a faulty chassis ground cause this?

[wvicary]

What RPM is that recorded at? Idle? A poor ground will reduce the potential of the charging system so it could be a fault. What is the voltage @1500RPM with no accessories on?

[rays_s]

I'm glad you also confirm that the 9x7 clusters had software glitches.

This is still what an expert also confirms to me - while the dealer denies it.

I refused to buy a new cluster yesterday just because the Airbag light does not come on anymore after coding a cruise control.

We'll re-program the cluster with a more recent firmware later this week and will see if that fixes it, in parallel I got another cluster for testing and comparing.

Because 9x7 series cars are known to have had some software glitches. Re-programming automatically updates the software/firmware to the latest versions.

[johnsnow]

I managed to fix it, there was a blown fuse for the 12v power (the one in the arm rest bit) and I removed the ciggerette fuse also. No idea why but cars works perfectly now

[wvicary]

That doesn't make any sense why a blown fuse would impact the cluster in the way you described. I hope somebody can explain it.

[Richard Hamilton]

What was the fuse number you changed?

[johnsnow]

What was the fuse number you changed?

It was A8 the thats the 12v one in the rear arm rest isnt it? (the one 2 to the left of the cigarette one on the first main row) Edited July 18, 2012 by johnsnow

[Richard Hamilton]

Yes, that's the one. Like wvicary, I was just trying to make sense of it, as there seems no logical reason why that fuse would affect the instrument cluster.

[Loren]

Yes, that's the one. Like wvicary, I was just trying to make sense of it, as there seems no logical reason why that fuse would affect the instrument cluster.

I agree with Richard that circuit does not handle the instrument cluster. The only way I see it could affect the cluster is if something attached to it was pulling the whole electrical system down (which could be a clue to why the fuse blew).

[johnsnow]

Yes, that's the one. Like wvicary, I was just trying to make sense of it, as there seems no logical reason why that fuse would affect the instrument cluster.

I agree with Richard that circuit does not handle the instrument cluster. The only way I see it could affect the cluster is if something attached to it was pulling the whole electrical system down (which could be a clue to why the fuse blew).

In terms of attached device? If so nothing has been attached since ive owned the car either that or the ciggerette connection. Maybe a faulty connection that shorted? Or a penny thats fallen down the console arm and possibly shorted(ing) it?