Okay, I have a 2001 1500 very base model with a 5.2L. The overdrive light would not go off after starting truck until shut off and restarted. A couple weeks later the O/D light would come on while driving and it would drop out of OD until I restarted the engine. The shifter button was doing nothing so I started with changing shifter button, no difference. Okay. so then I changed the shift solenoid, EPC Solenoid,Pressure Sensor Transducer Valve Body Filter; Speed Sensor, and the 3-4 spring(found mine broke in half). Put it all back together and now the OD light will come on randomly, shift button doesn't work, and the primary issue it will not go into OD at all. The transmission runs well and tight up through the gears. I will hear the 3rd gear and then I get the RPM lock-up drop but no OD. ( Yes, the fluid is all new with correct level)

My best educated guess is the PCM needs replaced. Does this seem correct?

 

How many miles on the transmission? Has it ever been rebuilt?

 

129000, I don't think it has been rebuilt. Have ran an OBD2 with no stored or pending codes. It is running around 2500rpm at 55mph. Also, replaced the fuse box relay.

 

Verify the switch is working.... it gets a 5 volt signal from the PCM, and when you press the button, it sends it back. Test that circuit, make sure it HAS 5 volts on it, and also make sure that when you press the button, it completes the circuit.

 

Thanks, I do that.

 

Finally got some time. Tested the button on shifter. The button itself tested good but I get nothing when I tested the connector inside the shifter. Tested with key on and both in drive and park. I get power at the PCM on gray 17pin for the over drive. I have power there both in and out of drive.

 

Is that the supply side? Or the return side of the circuit?

 

Not sure, it was an orange/white wire that was labeled "over driver off switch sense". There were no other pins assigned to that circuit. There are two 5v pin coming out of the PCM, one each from the white and black connectors. Both 5v pins have power.

I would think that the orange/white wire would be the return that tells pcm to disengage OD. If so, it should not have power on it and would indicate problem with PCM or short in wires to shifter button. My question is why does the dash icon come and go if no power to button and would that keep the OD from engaging? Still frustrated, my go buy use pcm to confirm my thoughts.

 

Ok, it appears your O/D switch works different from what I am used to.... Connector 3, pin 13, Orange wire/white trace, is indeed 5 volts from the PCM. The switch just grounds the circuit..... (G200, left side of cowl......)

 

Did some more digging and found that someone had removed the shift **** and twisted and broke all the wires in the gear shifter. replaced the column shifter and now the button works. So now the light works and the button now will engage and disengage the OD. It appears that my OD is working. My only issue is my truck seems to be running high rpms in OD. It is running around 2500 at 60. Not had a chance to take on highway yet.