1994 Jeep Grand Cherokee Speedomer and Overdrive not working



I have had the speed sensor changed after the speedometer quit working. It has not solved my problem My check engine light still comes on when I hit about 35 miles mph. and it seems that the car will not shift into overdrive. The spedometer is not working so are the two connected somehow?

My mechanic can’t seem to pinpoint the problem.

Please help me as the car is good otherwise and I realy can’t afford a new one right now.

Any ideas? Please Please

thanks so much


Sounds like a fuse that is common to both. Chech the discription of the fuses in the Owners Manual, it might help.


We thought of that too and went through and tested the voltage to all the fuses…they were all fine.
I am using way to much gas with the car this way…it runs at 3000 rpm since it won’t go into overdrive.

Thanks for any help or ideas


we did check all the fuses and the voltage to them is all good. any other suggestions pleaeeeese…I am using way to much gas driving without going into overdrive.
thanks for any help


thinking logically, seeing that the speedo is electronic, it get’s the “data” form the transmission, and if the transmission is not working correctly, then there is a “speed sensor” in the tranny is the problem. Where that may be in the trans I don’t know. If you can get under the cvehicle and look around, you might be able to find the connectors and the sensor.
Sorry I can’t help any more than this. Good luck.


What size motor is in your Jeep??



I’m just going to take a guess tht you have a 518 transmission. In this case, the speed sensor located on the tail shaft housing has a plug going to it. Check the wiring going to this plug, if the speed sensor gets disconnected, it will do exactly as you have stated, which is lock out O/D. A technician can easily diagnose this with a scanner monitoring the VSS reading.