I have had the tranny looked at and all looks good with no apparent reason for the problem. I rebuilt the OD unit and it did not cure the problem. Was told it might be the TPS yet passed all voltage tests. ??? Any answers???

 

Have you tried adjusting the TPS? On my 92 I had to "modify" the plate the TPS mounts on in order to get the correct amount of rotation on the actuator thingy. Other wise it kept shifting in and out at 55. If all else fails, do the rheostat conversion.

 

Not sure why i would adjust the TPS when it passed all voltage tests perimeters? Maybe i'm missing something? Could the TPS pass the voltage tests and still be malfunctioning? Heat sensor and OD solenoid are suspect at this time. When driving, what indications are there that it could be the solenoid or the sensor? Headed to ND for work and need info soon please!!!!!

 

My 92 was doing the same thing and when I installed my fuel pin I gave it a good hard rap on the top with a heavy screwdriver handle and it has worked perfectly since. I have read in other posts that the TPS can be a real pain in the a$$ but yours sounds identical to what mine was doing.

 

The voltage test only tell you you are getting the right voltage in and out, not if it is adjusted correctly.

 

Thanx 4 then info guys. another question is what exactly does the trans temp sensor do, i.e. what does it relay to? does it ground when up to temp? does it unground.. per se. and what is it relaying to when it does do what it is intended to do? Finally, where is it located? Thank you very much.

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What do mean by fuel pin?

 

The TPS tends to get a spot worn in it right around the position that equates to your normal driving speed (throttle). It's there that the required reference voltage drops out giving the OD a fit.

 

What is meant by "adjust" my TPS??? I'm having a hard time understanding that if it passes the correct voltage test, then why is an adjustment needed, how do I adjust it? And what would adjusting it be doing??? Many thanx!!

 

Tom,

Let me get home from the beach and I'll post the FSM instruction.

- Under the installed TPS, there is a black plastic piece that more or less, connects the TPS to the throttle shaft. A portion of that piece is threaded such that when you hold the throttle at maximum, using a wrench, you adjust that plastic piece so you get the FSM specified voltage from the TPS. IIRC, that voltage is in the 2v range (+/-). With that in mind, readjusting that plastic piece will allow you to alter when the overdrive comes in vs your highway speed.

 

I took some pictures of mine
TPS installed

Back side of TPS and the driver in idle position

Driver removed. Note the step. That is for a key on the driver that limits the drivers travel

You can, as I did, file the step further clockwise to increase the travel in a direction that will let you adjust the driver so OD will not down shift too soon.

This is the driver. Note the key and the bolt. The bolt drops into the top of the throttle linkage. You can turn the bolt in the black plastic driver piece. That is how you adjust the TPS

Considering our trucks are 20 years old and a lot of miles, I would not consider the adjustment voltage in the book as absolute. Adjust it to were you want it to shift.