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Topic: 86 TC speedo not working. (Read 1280 times) previous topic - next topic

86 TC speedo not working.

I have a 1986 turbo coupe that has a broken speedo. The sensor gears are good as I just pulled the sensor off. I also check the continuity between the speed sensor plug and the wires a little ways up and it was also ok. The only thing that I noticed when pulling the cluster out was that one of the wires on the plug was cut (black one of the two on the 7th pr0ng.) but it was working before and I don't see any possible partner for this wire. The tachometer also still works.

86 TC speedo not working.

Reply #1 –
Can we assume you have a digital cluster?  Also, I am guessing this is a manual transmission car being that auto's are pretty uncommon.  If it is a T-5 car pull the VSS back out (the driven gear is attached to this) and take a mirror and flashlight and look for the drive gear on the output shaft of the trans.  I know with the Mustangs the driver gear is yellow in color but I am not sure with the TC's.  Regardless I have read where the drive gear either comes apart or simply slides down the output shaft due to the keeper coming out.  If its an automatic car the output shaft has the drive gears cut into it so this is a moot point on them.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

86 TC speedo not working.

Reply #2 –
It's possible that stray wire is normal and doesn't go anywhere. My 87 has one as well that put me in a panic trying to find the other end. You need to look at the EVTM for your car to be certain.

I would pull the VSS out and test it. It is a pulse generator and makes its own voltage so it doesn't need to attached to the car wiring. Set your voltmeter to AC and probe the electrical connector while spinning the gear with a drill. The AC voltage should increase proportional to RPM. I believe 0-10vac. Irratic or no voltage....Replace the VSS.

Good luck
John