1994, 940, Speedometer Problem

[btdavis43]

My speedometer works sporadically. Sometimes it works, usually when it's raining. Most of the time it does not work at all. The odometer and trip meter work fine. Also the cruise control and tachometer work. From what I have read, the problem may be at the differential. How do I check this? Is it something I can do at home? Any help or advice is appreciated.

[billofdurham]

The sensor for the speedo is in the differential about 3" above the filler plug. Check the connectors for security and check for signs of corrosion or oxidation on the connectors and the sensor. Also check, as far as possible, the wires for signs of tears or breaks.

The speedo is electronic and problems can arise if any of the solder joints are cracked (dry joints). The only way to check for these is to remove the speedo and test every joint on the board.

Bill.