My speedometer on my 1997 f150 4X4 4.6L (no cruise) stopped working after I went through some water the other day. It stopped the truck and I found a blown PCM fuse (the big one). After replacing this fuse. I then noticed the speedometer worked at low speed up to about 20 to 40 mph and then just drop to zero mph. Now it does not work at all.
I have replaces the VSS(vehicle speed sensor) and checked all the fuses(inside and outside). I took out the GEM and the dealer could not check it, but wanted $223.00 for a new one. I’ve checked the plugs in the fire wall for the PCM and the 3 big one on the driver side, no corrosion.
Any help would be greatly appreciated.

 

hey, my speedo didnt work at all ..... 88 f150 5spd w/ cruise...

i pulled out the gear at the end of the cable in the tranny it had some wear, some dips in the teeth, but nothing MAJOR .. i replaced it anyways, and it seems to work ..although heres the odd part


when im on the gas or clutch, it drops about 10mph.. when im going at a decent speed and let off the gas it goes back to the correct speed... until im on the gas again ... seems like it has to be something electrical ...


any suggestions on that one.. ?

 

My mechanic told me today to start OHMing the wires. he said the PCM on these trucks don't go bad. But the salt from the roads will kill the wires in a few years. I've had it with replacing sensors on this truck.

 

We found it had a bad ground. Attached a ground wire to the floor board, right by the sensor and my speedometer is now working.