2000 Ford Ranger 2WD. Speedometer goes wild above 60 mph and the transmission slips in and out of gear. Anything below 60 MPH and it runs great. I have changed the Speed sensor 2 times. so that does not seem to be the issue. . any suggestions appreciated.

 

Welcome to the forum

Does the ABS light come on?

1998 to 2000 Rangers shared the speed sensor on the rear axle between speedo and the ABS system, so if that sensor fails speedo AND ABS will BOTH be effected

I assume the ABS light didn't come on

So next step is to check the GEM behind the radio

GEM is generic electronics module

The GEM has 2 two wires spliced into the ABS sensor wires
ABS sensor sends out 20,000PPM(pulse per miles)
Speedometer can only use 8,000PPM

So GEM gets the 20,000PPM and then Converts it to an 8,000PPM signal, then sends it out to the speedometer, cruise AND computer(for automatic trans shifting)
Since BOTH speedometer AND transmission act up at the same time I would say that the GEM is the problem, unless ABS light is on as well

GEM can be programmed for tire size, so is adaptable, might be worth a call to Ford Dealer to see how much to program it, and if they can't then no charge and you will know thew GEM has a fault, which you already kind of know but not certain

I would pull out the radio and check the 4 connectors on the GEM, pull them off and look for issues on pins and plugs

The Grey/black wire on pin 1 is the Speed OUT wire, it splits and goes to cluster, computer and cruise
There is another Grey/black wire on pin 9 of same connector, or could be Red/pink stripe wire, this is from the rear axle sensor, the speed IN wire

 

Thanks for the info. I don't believe my truck has ABS brake. I need to verify that. You have given me a lot of information to work though. Much appreciated.

 

It has at least Rear ABS, in 2000, 4 wheel ABS was optional that year

Yellow ABS light in the Dash should come on when you turn on the key and then go off if all is well

 

I've changed the sensor on top of the rearend. I'll check the GEM as you suggested. Thanks