Gauge cluster questions

[mgbrv8]

My speedometer has never worked on my 1987 BMW 325I. So I started in the rear at the differential and tested the pulse sensor. With my ohm meter I could read The switch opening and closing while I turn the rear wheels I then traced the wires( Brown with red and a brown wire) to the white plug on the back of the gauge cluster. And could read the pulse signal from there. So my problem wasn't with the wiring or the sensor. I have already replaced the plastic gears in the speedometer because my old ones had deteriorated. I also resoldered a number of different connections on the Speedometer board itself. The only things I have not done is change the batteries on the SI board because they arnt leaking in fact I haven't done any soldering on the SI board whatsoever cause it looks very good. Also I checked my all my fuses and they are good. Any insight or advice on anything else I could try would be greatly appreciated or recommendations on who to send my cluster off to to be worked on i see there are a few to choose from.


Dave

[Originale30]

I believe I’m in the same boat as you.... I haven’t done any physical electrical testing on mine as you have yours but I’ve narrowed mine down to being an instrument cluster issue, my speedo does work 90% of the time, randomly it will drop to 0 well driving and sometimes it will stay there until I give the instrument cluster a flick with my fingers and the speedo turns back on, my SI board and batteries look good and the service lights work and rest perfect.... since you have done tests to rule out other issues, it looks like your problem is with the instrument cluster as well... my next steps are to take the instrument cluster apart and look for broken solder on the electrical boards... any issues with the circuit board or even the pins to the connector will cause the speedo not to work, if you search around you’ll find some pages online or posts here in the forum discussing the circuit board solder problems, good luck!!


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[mgbrv8]

Thank you for the response and unfortunately mine dosent respond to a tap or a knock at all. Please keep me posted on your issues maybe we can help each other on this issue

Dave

I believe I’m in the same boat as you.... I haven’t done any physical electrical testing on mine as you have yours but I’ve narrowed mine down to being an instrument cluster issue, my speedo does work 90% of the time, randomly it will drop to 0 well driving and sometimes it will stay there until I give the instrument cluster a flick with my fingers and the speedo turns back on, my SI board and batteries look good and the service lights work and rest perfect.... since you have done tests to rule out other issues, it looks like your problem is with the instrument cluster as well... my next steps are to take the instrument cluster apart and look for broken solder on the electrical boards... any issues with the circuit board or even the pins to the connector will cause the speedo not to work, if you search around you’ll find some pages online or posts here in the forum discussing the circuit board solder problems, good luck!!


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[cheffy30]

perhaps tighten all the nuts and screws inside the cluster. i did that to mine when i had no response and all works fine now. change all the bulbs while you're at it.

my 2¢

[mgbrv8]

Thank you at this point I am trying anything

Dave

perhaps tighten all the nuts and screws inside the cluster. i did that to mine when i had no response and all works fine now. change all the bulbs while you're at it.

my 2¢

[faber]

Pop the cluster out, pull all the screws on the back panel and open it up. You need to make sure the connections tha gauges make internally are clean and there are no broken traces. Sometimes people put screws in the cluster that are too long and portrude through to the board and break traces. Address any broken traces by scraping the traces to expose the copper and solder a jumper wire to repair the break. Also get some contact cleaner and spray down any connectors. they can get a little corrosion and stop making good contact.

I have been fighting cluster issues as well and they seem to be mostly bad/intermittent connections in the circuitry.

Hope this helps!

[cory58]

This is why I'll be sending mine to Bavarian Restorations.