Speedometer Issue with 1993 240 sedan
My speedometer is intermittent- it works sometimes but mostly not. All other instruments and lights are functioning in the cluster.
it has the K40168 unit. I get voltage with a meter on the blue and black wires. Is it the plug contacts? The circuit board contacts? Is this common?
Also, can I substitute a K10042? Will it be inaccurate but work?
Thanks for any help!

 

I don't know what the differences are between K40168 and K10042 but they may have a different connector running to the speedometer (one a 3 wire and one a 4 wire). I know they changed speedometers sometime around '91 when they added the anti-lock brakes. This required a different tone ring in the differential that generated a different number of pulses per rotation and required a different speedometer. More than likely the speed and distance (odometer) would be incorrect.

Take a look at these sites:

Electronic Speedometer Notes
cleanflametrap.com
1989 Volvo 240 Speedometer Diagnostic

One of them may be useful in your diagnosis.