Application : 1988 Formula 5.7L Automatic 700R4

so when we had the rebuilt transmission put in it came with a different speedometer sensor. I know this because, the existing wire harness had a secondary harness piggy backed on the same harness to plug in the to speedometer sensor. ( there are 2 plugs with different plug both 2 wire contact.) we drove it for a while. speedo worked on and off.. a year goes by. i get a speedo sensor from the wrecking yard... plug it in, obviously one of the plug formations should work. and it did. pluged in.. turned the car to the on position and had a friend sit in the car while i spun the gear on the sensor . its working she says 10 20 mph.. great... i take the existing sensor out of the tranny and put the one i tested in the tranny and it doesnt work.

i tried putting the gear on the sensor i took out, because it was worn so it looked like.

the damn thing doesnt work still.

im frustraited.. i think im gonna go get a brand new speedo sensor and work from there!

 

Don't forget there's a plastic gear on the tail shaft of the transmission that likes to crack and slip on the shaft.
Take a look up in the hole while rotating the driveshaft slowly.
See "style B" in this picture.