My 940T speedo mostly registers up to 45 MPH but usuallt does not go higher. Occasionally it will indicate the actual speed, in cool weather and ?? cnditions.

My question is it worth having the unit serviced and repaired or should I replace with a used or new speedometer? The odometer works fine and always has. The speedo gradually tops-out at a lower speed during a long drive.

Could this be related to the ground screw or loose connection? It seems like mechanical drag to me. The car has 248K miles in SE climates. The needle does not jitter or spike when traveling below 45.

This is a fault within the speedometer. http://cleanflametrap.com/speedo7.html

Oops, both Amarin and I fell for Blindboy's raising from the ashes of a 17 year old question.
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Art Benstein near Baltimore

"Politics is the systematic organization of hatreds." -Henry Adams

"Oops, both Amarin and I fell for Blindboy's raising from the ashes of a 17 year old question"

We're all true-blue Brickboarders! Many more others too!

Regards,
Amarin.

I asked Jarrod to consider highlighting a thread's title based on its origination date being aged. However that request itself is aged now.

As to the 45 situation, it is the result of either electrolyte damage or repair technician damage that opens one of the two loops in the quadrature coil. Caps will leak and still do their job after the electrolyte has destroyed the circuit foil.
--
Art Benstein near Baltimore

Always remember that you're unique. Just like everyone else.

Check both the differential and speedometer. Haven't experience this before. I mostly guessing some wear particles might be messing with the speed sensor at differential. Sensor could be taken out and cleaned. How long since you replaced the diff fluid? Less likely to be speedometer circuit issue (leaking capacitors) as yours works out well during long drive. Once a capacitor fail it will stay fail.

Amarin.

I have a 92 740 turbo speedo will that work??908-343-1939

First check the rear axle sensor, connector and wiring, along with the instrument panel grounds. See the FAQ for locations and information. IF they check out, then assume the speedo needs servicing. Again, the FAQ has tips.