I finally got my car back from getting the transmission rebuilt and having the super bearings installed. Now my MPH gauge does not work. Does anyone know how to troubleshoot it? The car can drive now and shift smoothly.

 

The MPh impulse sender is on the transmission and may not of been hooked back up properly.
They moved it to one of the front wheels in one of those later years. Some one who has a later car can hopefully chime in and give you a better answer.

 

Look on the back of the differential case. The sender should be there and the wiring goes into the spare tire well.

 

Tony do you have an image. Am I looking at the differential case and not the transmission part like the very back? Thanks

 

On the back of the diff on an 89 IIRC. Round at about 1.5" with wire running upwards towards the spare tire area as Tony said.

 

thanks ill take another look and send some photos

 

What work did you have done?
If it was internal to the differential case there could also be an issue. Something about the pick up being located in a different spot internally? I think Darien had an issue with his once he got it back from a shop also.

 

I had the transmission rebuilt.

 

I looked at the green cap on the back of the differential that a wire goes into. Its still in and it looks like some kind of retaining pin is still holding it in.

 

Could be the speedo itself I have repaired 4 here in the last month....Quick rivet solder on the circuit pannel, got it down to 30 mins a car. On a 78 that is.....them are really easy to fix

 

How do I check the meter itself. The digital mph readout also does not work

 

 

was that the sensor you were talking about? that is the one i checked, the picture was taken during the dark.

 

does any one know Darien's user name? i am trying to find out what he did to fix his speedometer. Is their any test I can do with a multimeter?

 

This happened to me. I think the same thing happened to Darien. If the diff was not replaced, this is not the cause here.

The diff issue has to do with swapping in a diff from 83-85 into 86-89 trans or vice versa. The diff will fit, but the speed sender magnetic ring in located in a different spot, shifted over 1 cm, enough to not work unless the diff cover for the diff year is also swapped. Many people update the drivetrain to limited slip, like I did, and a limited slip from 83 on will fit any later year case. But care must be taken with model year to get the right cover as well.

https://rennlist.com/forums/928-foru...fferences.html

George Suennen had the magnetic ring come loose in his 90 diff. The way the ring is retrained in 90 with the PSD is different than in 89-. I don't see how it can come loose in an 89- diff. In George's case, we isolated the problem to the diff by simulating the magnetic ring with a few magnets glued to a sanding disc. As we rotated the disc in a variable speed drill and the magnets passed the sensor we could see the speedometer readout working perfectly. That pointed to a problem with the magnetic ring, and sure enough, the ring was loose and busted into fragments. It took us quite a while to narrow this down and we went through studying all the electrics first.
https://rennlist.com/forums/928-foru...r-failure.html

The most likely cause in the current case is the sensor harness connector in the spare tire wheel well. That is shown in one post in the previous thread as we tested the sensor, which can also fail.
https://rennlist.com/forums/5669450-post11.html