Cluster issues

A good place to start is the Body Electronics Module A25 which lives under the left-hand side of the dash (above the kick panel). There are three modules there and all can be affected by moisture. Of course, the instrument cluster itself can be at fault, but it is A25 that drives the instruments. However, you can test the cluster itself by holding the trip-reset button down while you switch the ignition ON:

https://www.youtube.com/watch?v=B7EL3raLW5A

If the cluster passes the test then the problem is highly likely to be the A25 module. I've never had to fish out the modules above the kick panel so can't say how difficult it is. But, I have seen pictures of the damaged modules and it is quite evident!

Have you done the cluster test?

The E31 instrument cluster and the body electronics module (EKM) form a pair and in case of problems it's often very difficult to isolate the problem to one of both.

The instrument cluster test is not a good indication. For example, member sandwich had a cluster with all gauges dead except for the speedometer. In the instrument cluster test all four gauges operated normal so it was assumed the fault had to be the EKM. In the end it turned out to be the instrument cluster after all...

Visual inspection of the modules is a good start but no visible damage does not mean the module is not faulty. A simple thing like an aged electrolytic capacitor which is not yet leaking but also no longer in-spec might cause faults with no visible damage.

Another thing to try is the service menu on the MID (see instructions to unlock the service menu). After unlocking the service menu, select entry 08 (current speed) and drive a short distance. Does the digital speedometer work? If yes, the EKM is certainly not dead and it might be more proof that the fault is in the instrument cluster, but it's no guarantee.

You may also wish to read the fault codes from the EKM module.

If there are no signs that clearly hint at one of both modules, the best and quickest way to identify the faulty module is by simply replacing the instrument cluster. If the problem persists, it's the EKM. If it's fixed, it was the instrument cluster. By replacing I do not mean buying a new one from BMW which is ridiculously expensive, but either borrowing one from a fellow E31 owner or scoring a cheap second hand one. Please note that you can't simply put a used instrument cluster in your car - the gauges will remain dead and the odometer will read EEEE. You must first reset the used flag with BMW diagnostic software (see instrument cluster swap).

Another module in the car, the A1 general module (GM), is notorious for its failing electrolytic capacitors. Electrolytic capacitors have a finite life span and the ones used in this modules are not of the best quality. Replacing the bad capacitors with new ones is very cheap and has a high success rate. It has been suggested that similar capacitor issues could be the cause of issues with other modules, like the EKM or instrument cluster. Note that there is not any hard proof for it yet. Nevertheless, if you are electronics-savvy you may wish to replace the electrolytic capacitors in both EKM and instrument cluster.

Please be more verbose. You replaced fuses, which ones (they are numbered) and were the original fuses blown?

Judging by your earlier posts describing the warning lights and instrument cluster test, all fuses from the instrument cluster (F1, F17 and F55) looked okay.

Was the instrument cluster back working a direct result of replacing the fuses (in your opinion)?

Zitat von Tor K;131688

Now the cluster instrumentpanel working, but the distance and trip meter illuminates even when the car is locked.
...

As far as I remember this is exactly one of the common behaviours of faulty Electrolytics in the EKM and/or Cluster...
You won't be done with just some Fuse swap... I'm afraid

Tor K: A fuse holder with only two fuses of 10 and 25 A? That has to be the auxiliary fuse box and the fuses are F50 (10 A) and F51 (25 A). These fuses are used only for the park ventilation/heating system (if equipped). So unless someone has gone creative on the wiring, I'm afraid that fixing the cracked fuse holder has nothing to do with the instrument cluster coming back to life. It's probably just coincidence and the instrument cluster can probably die any time again.

There have been quite a few reports of the odometer lights staying on. The problem is that most cases did not report back with a solution (if there ever was one). Some mention low battery voltage (so make sure your batteries are good and charged), one person had luck with disconnecting the factory car phone (although the issue returned later), another found that a broken door handle kept triggering the microswitch and prevented the car from sleeping, but by far the most common issue appears to be with the instrument cluster itself. It's not clear what exactly is wrong with it, but replacing the instrument cluster fixed the issue for several people.

Danilo: Do you have a link to a topic where replacing the capacitors fixed this particular issue (odometer lights staying on)? I know of several topics where replacing the instrument cluster fixed the issue, but I could not find any of a successful repair (or even an attempt).

One of my test instrument clusters has a badly leaking capacitor but so far it's not causing any funny behavior. I've cleaned the electrolyte from the PCB so it can't do any further damage but I did not replace the capacitor. I'm somewhat hoping it will act weird in the future so we'll know for sure replacing the capacitors fixes anything.

Nevertheless, replacing the electrolytic capacitors is probably a good starting point, though. Capacitors are dirt cheap and even if doesn't fix the issue, it doesn't hurt.

For anyone wishing to replace the electrolytic capacitors in the instrument cluster: The instrument cluster electronic backplane is not meant to be serviceable. The PCB is mounted to the frame with plastic rivets which have to be drilled. You will not be able to reuse the rivets but try to avoid damaging the plastic studs any further than required. For those deciding to replace the instrument cluster instead of repairing the bad one, please consider donating the bad one to a member with electronic skills so, maybe, something can be learnt from it...