1992 944 b230ft 100K Both the speedometer and the odometer are not working.

I drove the car to the airport parking lot and all was well. A week later upon exiting the airport the odometer/speedometer was not working and has not worked since. The only environmental influences might have been two days in the 90’s.

Today right before starting to look into the problem the speedometer would jump to 45mph simply by turning the key to the position that causes the dash warning lights to come on. It continues to do that but then drops to zero after the key has been on for 30 seconds or so.

I have checked/cleaned the sensor connector. I have cleaned the connector in the trunk. The brown/white has continuity to ground at the connector in the trunk.

The multiwire connector on the passenger A pillar seems fine. No corrosion found anywhere at the connections.

The connector at the speedometer seems snug after removing and lightly cleaning it.

I have the rear of the car on jackstands at this point. When I disconnect the speedometer and try to check the signal from the green/white wire (using the brown/white as the ground) at the connector. I get inconsistent readings that range from zero up to what appears to be 3.4 mv. It shows zero with the brake on an progresses up to 3.4 which is at a shift point (the second one I believe) but no matter how much faster the wheels are driven at that point the voltage does not do up above 3.4 and 3.4 microvolts seems very low to me.

Anybody have any suggestions or additional tests to conduct? Thanks.

Randy