'93 6.5 Turbo diesel Transmission fail codes

[DaveOmak]

Truck delivered October 1992... One owner... 110,000 miles..

Transmission shifts VERY hard... No overdrive... It can be reset by disconnecting the battery and all shifts fine for about 5-10 minutes....
The fail code is TPS failure.....
One mechanic told me that is a default code.. there is no TPS...
(Is there a Throttle Position Sensor ??? I couldn't find one and there is no replacement part #...)
and the fail code denotes a wiring problem.. bad connection, bad ground, etc...
I have been told this is a "Hunt and Peck" fix.... Leave the truck and we will try to find the problem....

Now that would be fine if I still lived in Bellingham Wa. where my transmission guy was really good... Brad Barrett Transmission Specialties...


So, what I need is some pointers and possibly a wiring diagram of which wires connect to the "system" that controls the transmission...
Where to look on the engine, chassis and transmission for wire faults... Colors of wires would be a really big help also...... If I'm leaving something out.... please fill in my blanks......


I do have a dependable mechanic that works hard at keeping up with new technology... He has a couple good guys working for him.... Between the 3-4 of us we might make headway...

If I could drive the truck to Bellingham, I would... It's 200 miles and I don't think that would be a good idea...

[trbankii]

Since I was just looking up TPS numbers for another thread, here’s the number for a ’93 with a 4L80E - ACDELCO Part # 213879.

I’m going to say you probably don’t want that mechanic working on your truck… ;)

[56pan]

Next time it does it, pull over and shut it off. Wait about 30 seconds, turn the key to on and off several times. Then start it and see if it still shifts hard and has no o/d. If it does not, it could just be worn contacts in the ignition switch passing a reduced voltage to the trans. The reduced voltage will cause the trans to go into default mode. Full pump pressure, hard shifts, and no o/d. Hope this helps.

[john8662]

Sounds like Bad or mis-adjusted TPS. Search this forum for how to adjust and test the TPS. Only tools required is a DVOM (Digital Volt Ohm Meter) and a 10mm box end wrench.

[DaveOmak]

john, 56 and tr..... thanks for the info.... It's copied and I will test it out....