91' wont go into O.D.??

[powerchoke-eatr]

just bought a 91' D350 2wd that wont go into overdrive. what can i look for or check? i noticed a pressure looking switch on one of the tranny lines with a broke end with no wires does that control it? thanks mike

 

[Cummins Driver]

If it is the transmission temperature sensor, that could be your problem. On the 2nd gen trucks, they dont have a gauge on the dash for trans temp, but they do have a sensor in the line, and the computer does get a reading from that. If the trans temp isnt hot enough, it wont let overdrive engage. I know you can use a resistor to jump between the 2 factory wires going to the sensor. That is how I have mine. i think it is a 1k ohm resistor, but im not 100% on that. Good luck.

Eric

 

[ME.]

You should have a 518 non electronic tranny. The throttle position sensor (tps) controls OD. You can check and adjust it. Or if you have a wiring problem or something you can just run a ground wire to a manual switch and connect it to the OD solenoid on the tranny and control it whenever you want.

 

[powerchoke-eatr]

thanks for the help guys...can you tell me how to wire it up that way on the tps? or is it cheap enough its worth tryin to swap out?

 

[921stgen]

Here is some reading material for you it might not help if the wires are broken off but for the future. I have a couple of links 14 posts down. http://cumminsforum.com/forum/89-93-performance-parts-dicussion/78805-potentiometer-mod.html