Speedometer problem help?

Question

My speedometer doesnt not work on my 1990 BMW 325i however the odometer works fineand Temp gauge and Fuel gauge, sometimes the speedometer just tells the correct speed for like 2 seconds and then it jumps back down to 0. I think its a wire or the Si board but I am not sure, any suggestions on how to fix it?

Answer 1

The left rear wheel speed sensor should be cleaned first (just as a precaution).

Then the cable connectors at the back of the instrument cluster must be checked also to see if they are properly connected. Detaching the cluster is very easy. Just remove the 2 small screws at the top edge and you can then pull it out.

If both are OK, which I think they are, and the speedo still goes intermittent, then you need to replace the cluster since the motherboard is not available separately for this model.

A new cluster needs to be coded.  A good used cluster could be your best choice. Good luck.

Answer 2

Have you tried lightly tapping on the dash?  IF it is a short, that might tell you something if it tries to jump back up. I would try some BMW forums online. What is bad is that if has to be removed, the steering wheel may have to be pulled. And if it has an airbag, it will require the services of a professional who knows how to remove these and has the tools. My 1991 318IS had the airbag.  Not sure about 1990 cars.  I wish you luck and hope it is something simple. Hopefully a BMW tech will read your request.

Answer 3

HI !

First off....

The other answers are all wrong. PLEASE ignore them.

I have seen this problem many many times in BMW's. The Speedometers Main Circuit Board has a bad Solder Spot.

Remove The Speedometer and have it repaired by a proffessional or replace it with good used or new unit.

I would have it repaied myself as it is easy and painless.

If you lived in San jose California: I would charge you $120 to remove repair and reinstal with 2 year warranty...Would take me about 1 hour to do the whole job at you house or place of work or anywhere.

I hope this helps..Good Luck!

Answer 4

I did miss the part about it working for 2 seconds.  And that can be a bad solder BUT this particular speedo has problems with the actual components on the bard that causes the 2 second and off thing.

if the odometer is working you have a bad speedo board or the part that actually moved the needle.  Its a either or thing. Little hint the needle will come off if you pull straight up.  I made a tool to pry them off without damaging the thin steel of the needle.

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Yeah go ahead and listen to the SPEEDO MAN I know nothing about what I am talking about.  Just had a 3 in today with the EXACT SAME PROBLEM. There were NO bad solders on the board (as BMW usually has on the NEWER BMW)   This time the speedo had BAD electronics.ACTUAL COMPONENTS.  Swaped the board and now its fine.  AND

FYI they took it to a speedometer shop and they FAILED.