E30 Speedometer Repairs - Failure Modes

[jlevie]

The speed signal from the differential goes to the cluster, then to the OBC and cruise control.

[nando]

The speed signal from the differential goes to the cluster, then to the OBC and cruise control.

and DME.

[dj_Roo]

Capacitor failure. It is a common issue that occurs on the VDO speedometer. On the board of the speedometer head lives a 220uF electrolytic capacitor.

I just replaced the bad gears in my VDO unit and still no odometer movement. I did see the discoloration on the pcb that 03IRM3 mentioned so I wanted to try changing the capacitor. Does anyone know what type of cap I need? I'm handy with a soldering iron but don't know crap about the differences in components.

[cory58]

I also get much satisfaction from figuring things out, but it was really easy to send my cluster to Bavarian Restoration. bavrest.com

[Carmeyer]

I'm in the midst of trying to fix my motometer odometer. So far I replaced the gears and the odometer started working but I noticed the backlight for the speedometer and fuel gauge was out. So out came the gauge cluster again. Luckily it was just a bad bulb but I broke the A tabs off the cluster when I was reinstalling it.

At this point I have repaired the A tabs and reinstalled the cluster. But on my test drive the odometer worked for less than a mile. So I pulled the cluster back out. The gears were all aligned and the small drive gear is turning the other gears and the odometer is advancing. However, I noticed some binding in the gears and I found a few small bits of plastic on the gears. I am 99% sure the bits are from the holes I drilled when installing the A tab repair kit. The repair kit was from German Iron and the repair tabs are attached to the housing with screws. Fit and finish of the repair tabs is very nice, btw. I blew the bits of plastic off the gears and everything is turning smooth now. I have not reinstalled the cluster in my car yet because it's getting late. I will report back after I get it back together. I sure hope I found the cause.

[Carmeyer]

Good news, my odometer is working now. It must have just been the small bits of plastic on the gears, as I mentioned in my earlier post.