This is on a 95 2500 with CTD and 47RH transmission. Background info: Truck had a terrible transmission fluid leak from multiple locations. The fitting for the cooling line that hooks into the converter was leaking along with one of the other lines and the pan. I changed the pan gasket and filter and fixed one line. I noticed it was still leaking from somewhere and found it was the fitting for the line going into the converter. I took it to a mechanic because I wasn't going to have time to fix it. He changed that whole line out and saw that the speed sensor at the back of the tranny was leaking. He said it was busted up pretty good but he sealed it up. When I got it back, I noticed that the speedo didn't work and it wasn't going into overdrive. I took it back and he said the sensor was so brittle that it probably just needed replacing. I brought it home and just changed it out myself. The speedometer and overdrive still is not working. Everything else seems to be fine. Any ideas? Thanks for the help.

 

Pcm needs to read speed so it knows when to engage the od. If you replaced it and checked all the fuses i would look at the connector or wiring harness for a break or bad connection.

 

You should have the vss on the tailshaft of your trans, or t-case.... depending on how many drive wheels you have. So, which part did you replace? The sensor itself? The gear? Are you getting five volts TO the sensor?

 

It is a 4X2, so it's on the trans. I changed the actual sensor. I did not change the gear inside the transmission. I am getting around 9V to the sensor. Does that mean it's the gear inside the trans that the sensor fits into the middle of?

 

Also keep in mind that the sensor is indexed. If you put it in wrong, (which the guy fixing the leaks may have) the gear on the sensor doesn't mesh with the gear on the shaft of the trans. (I suspect this may be your problem.)

9 volts seems like an odd number to me.... .but, since you are getting something...... look elsewhere for the problem.

 

Forgive my ignorance but what does indexed mean in this case?

 

The hole the shaft for the drive gear goes into, is NOT centered in the sensor. By turning the sensor so different markings on it line up with the 'index' mark on the case, it changes the distance from center of rotation for the driven gear, to the drive gear. If you pull it off, and look at it, I think it will be clearer.

Make sense to you?