I found info on this board that suggested just disconnecting the TPS and the tranny will shift into OD on it's own. Poster said they had used it trouble-free for a few years.

I understand that the TPS is just a potentiometer and how it works. What I'd like to know is how it affects the OD shift point and how the lack of a TPS would affect the Tranny.

I've also heard of hard-wiring the connection to the TPS and fixing the TPS at 1.3v both as interesting solutions. Anybody have more info?

 

I started with my TPS voltage at 1.2 v and it would not shift into O/D at all. when I dropped it to .6 it shifted at 45, and at .8 at 55mph which is where I left it. I have seen it permanently set to a given setting and removed from the pump so it wont move. a cotter pin was used for this. its in one of the posts here somewhere. they liked it that way. I think this might give cruise control issues however. not sure though.

 

Here's my idea - I'm gonna try it this weekend:

I'm going to buy a 5k(?) Potentiometer (dial-type). Disconnect my TPS, lengthen and re-route the wires to the potentiometer and mount it near the OD on-off button on my dash. I can test it out and label it and basically "dial-in" my OD shift-point, meanwhile ditching the troublesome TSP. Plus, you don't have to worry about a waterproof pot if it's in the dash panel! Sound do-able?

 

Please keep us posted of your results. Sould love to dial my OD. Normal during normal days, higher for those full blown race down the road days.

 

Disconnecting the TPS on my truck caused it to not upshift to OD at all. I was having problems with the OD upshift as well because I had ground my throttle shaft linkage and bent my gas pedal to get more travel out of throttle lever to take full advantage of my gov spring but still be able to have a normal low idle. After modifying my throttle linkage the extra range took the TPS past its normal limits and would not allow an upshift at WOT. Here is a copy of a post of how I modified the TPS and bracket to get a WOT upshift. It has been like this for about 3 months now and is working great



Did some more tinkering today, wow am I ever having a blast with this!

Decided to pull out my nylon washer and shave it down. It was .144" and I took it down to .100". Did not seem to make a difference that I could notice.

But while I did have it apart I found something interesting with the TPS . Since I modified my throttle linkage to get more travel I have not been able to get a WOT upshift to OD. Even at 3000RPM and 75MPH. What I found is that with the extra travel of the throttle my TPS was reading over 4.0volts at WOT. This is with it adjusted all the way down so that it read 0.2V at low idle. So what I needed was to be able to turn the TPS down lower.

Once taken apart I could see that the TPS has all small block like a keyway on the shaft that moves inside a little window in the mounting bracket for the TPS . This little window controlled how far it would go on the high side and low side. My problem was that it would not let me 'retard' or turn the TPS down low enough so that at full WOT I would have a voltage of less than 4.0V.

Solution: grind back the window to make it bigger allowing the TPS to be turned down farther. So I ground back the stop a bit, didn't take much. Then I installed the TPS back onto the bracket and backed it off as much as possible, at this point the spring in the TPS was completly unloaded and just sort of floating. Then I carefully indexed the Hex nut on the TPS to the throttle shaft so that it would drop straight on. Then I installed the TPS/bracket assembly. I originally set the TPS voltage for 2.4V at WOT(don't worry about the low idle voltage). On the test drive I found at WOT it upshifted at about 45MPH. Way too low but atleast I knew I was on the right track! Adjusted the WOT voltage upto 3.0V and then had upsift at 55MPH.
Adusting WOT voltage to 3.4V then resulted in upshift at about 65MPH. Going to try it there for awhile and see.

Basically what I have done is moved the TPS back so far that it takes about a 1/4 of the throttle travel before it acts on the TPS making a voltage change. This can been seen by watching the voltage while slowly advancing the throttle. At rest it is .2V and does not rise untill the throttle is advanced about 1/4 of its travel. Then it rises normally to the value you have set.

Also I have noticed that the one hill I pulled it seemed to delay the upshift about 5MPH. So it still reponds to load changes.

Hope this helps some people, I know it was really buggin me!

 

I tried that today trying to resolve my shifting-in-and-out-of-OD problem. All it did was prevent the tranny from shifting into OD at all.

I gave that up as a bad job!

 

There is also a temp sensor which is supposed to prevent O/D from comming in if the trans is cold. it should be on your trans line out from the converter. maybe this is bad also?

 

Hi Apache,

Hmmm. My truck had been running all day when I disconnected the TPD. OD wouldn't come on at all. It makes me think that either I don't have one, or it works as it should.