i gotta 91 3.9 4x4 auto that has been giving me serious fits about not wanting to shift into overdrive, i replaced the speed sensor(twice) the first replacement snapped the little shaft that inserts into the transfer case, so i had to pull out the whole assy and get the shaft out and i replaced my transfer case fluid while i did that, second replacement showed no improvement because the odometer still isnt spinning and the pcm is STILL throwing a code 15( no speed sensor signal) which is why i replaced the sensor in the first place, and now, the main reason i posted this thread, is because my pcm wont reset the codes! i disconnected the batt and disconnected the wires going to the pcm and still throws a 12 15 35 and 55 before i even start the truck every time. ive checked all the wiring for breaks and nothing, i am at a complete loss... im about to either do a manual swap( if i can find a dang transmission) or drive it to the junkyard! PLEASE, any suggestions will help...also if anyone is an the NW florida are and has a manual trans that will fit my truck along with drive shafts transfer case clutch etc. etc. i will gladly buy it, even a 318 5spd drivetrain will do

 

First you said your odometer isn't spinning, so your speedometer is working but not odometer? Both are controlled via a cable that connects from the speed sensor, that could be broken which would cause the speedo and odometer to not work.

Since your getting the speed sensor code it sounds like you got bad wiring. Get a muliti-meter and test for continuity to and from the PCM and power and ground supplies for the sensor.

 

spedometer and odometer are both not working, how do i test for continuity with a multi meter?