i have a 1995 ford econoline conversion van and i am at a loss on what the problem is. the speedometer/ odometer stopped working and its causing a hard shifting transmission. i checked the fuses and replaced the speed sensor with no luck. i figured it was the PSOM so i sent the instrument cluster away to a company that fixes them and they replaced the PSOM. when i got it back it still didnt work! i sent it back to the company and they retested it, said it was fine and even put my instrument panel in a different van and said it was working. so i figure its a wiring issue? i tested the wiring harness that plugs into the PSOM for continuity and continuity was there. could it be the ground? any advice? anyone have a wiring diagram?

 

Yes a ground can cause problems. You might check if there's a dedicated fuse supplying power for the speed sensor circuit. You say you checked all wiring between the speed sensor and cluster? Small possibilties include a faulty new speed sensor or something internal to the transmission or differential not pulsing the speed sensor. I am not sure on the Econoline exactly where the sensor is located. Although you have a vague OBD 1 system, I would still do a code scan.