Speedometer not working

[Keith W]

I have a 1984 325e that I have restored and almost complete. The Speedometer and odometer do not work. Where do I start looking to fix the problem? The tacometer works.

Keith in Indiana

[winfred]

usually the pick up in the diff is dead, it's not a ac pulse generator like most cars it's a magnetically triggered switch, you can test it with a multimeter set to diode where it beeps when current is allowed to flow, should pulse as the axles turn

[Keith W]

If the sensor is dead, what kind of job is it replacing it. Does the differential need pulled and can I get the part at a catalog parts supplier?

[billb]

If the sensor is dead, what kind of job is it replacing it. Does the differential need pulled and can I get the part at a catalog parts supplier?

You'll replace the sensor and its attached o-ring. No need to drain the diff, unless you're replacing the fluid. It's visible from the rear of the diff, and can be changed without jacking the car.

[markn325e]

I have a 1984 325e that I have restored and almost complete. The Speedometer and odometer do not work. Where do I start looking to fix the problem? The tacometer works.

Keith in Indiana

The Speedos were made with a PC board on the back. The board through the course of years expands and contracts because of thermal expansion. If you examine the solder path on the PC board you will notice fine cracks that are basically causing open circuits. Go over, very carefully, these circuits with a soldering iron to reflow the solder. I had to do mine a few years ago. Also check the sensor in the Diff. cover. Most likely it is the speedo.