I have been reading all I could find on the TPS and I am tackling it today. First off, my transmission will drop out of overdrive when I let off the accelerator at any speed. My TPS connector does not have a black wire. Doing a continuity check I determined the blue wire with orange stripe(closest to front of truck) to be ground. I stuck two safety pins into back of connector, anc checked voltage from that ground wire and the centerwire(orange with black stripe) My voltage read 4.52 at idle position and 2.93 at WOT. That seems backwards from everything I have read. Think I should take the TPS apart or can I adjust it with that much voltage difference?

 

The "book" says the starting voltage should be 1.00 vdc and that the total increase over that base voltage will range between 2.25 and 2.75 vdc higher.
Now most everyone (including me) has found that the baseline voltage is ONLY a staring point.
I have seen them set as low as .45 vdc and some upwards of 1.25 vdc.
Your setting is based on YOUR need to have the 3 - 4 and 4 - 3 shift happen when you want it to.
The one important thing here is this.... as you open your throttle to WOT, you should see your voltmeter move upward in a nice smooth move. It should not twitch, spaz or hop around. If it does you've got an "iffy" unit.
Last the total INCREASE over the baseline is normally in the range of 2.25 vdc and 2.75 vdc.

That pretty much covers your question on idle or "at rest" voltage as I like to call it, and the increase values.

Let me know if this is helpful or if you need more info...

regards, bob...

 

Thanks for the input Bob. I got it going yesterday. I don't know why I had those crazy readings to start with. I tapped out to two metal sleeves and elonganated the hole. I got it adjusted to .57V and a tad over 3V. Took it for a spin and it is shifting great. Not dropping out of OD like before.

 

QUESTION:Mine is ok for a couple hours, than after driving for a while and the weather warms up during the it starts it's dropping out of O/D and won't stop.However, i unplugged the TPS and drove a mile,then re-plugged it back in and it worked just fine for another hour ...can anyone explain this?The unit looks fairly new from the outside, but i guess this doesn't mean it can't be bad correct? please help..

 

TireHauler04
I would check the voltage. You may need to just adjust it like I did.

 

Bob, in adjusting the TPS to shift properly at normal driving seems to work great. But when giving it WOT getting on the highway or whatever , mine seems to hang going into OD unless I let up on the throttle a little. Would that still be just an adjustment on the TPS (lower the voltage more) or could that possbily be the TV Cable (auto) going to the tranny?

I have had it stay right up to the 60 - 65 speed before letting up on the throttle. Maybe I just need to install my 3000 GSK to help in this matter.

 

It sounds like you need to tweak the throttle valve cable a tad...use care though....
It only takes a bit to make a difference and if you go too far in any direction you can start to increase wear and tear due to slippage/improper shift points etc.
In fact the correct way to alter a shift timing is using an adjustment inside the pan, on the VB itself.
You can however use the throttle valve cable for slight tuning as needed.

With this topic in mind and, if you haven't done so in a while why not drain and do a service. Change the filter, check your band setting and refill it.
Then you can fine tune the shifts knowing it's nice and clean with good oil...just a thought.


pastor bob.....

 

Thanks Pastor. I usually change filter and fluid about every 18,000 - 24,000 miles. But, the bands have not been adjusted for maybe 35,000. I think it is time and I usually have Mass Diesel (they installed my DTT) do this. Always nice to have someone else to check out the truck on some things. I know it is just a torque to 72 lbs/INCH and then back off though. Maybe it is time to do this as winter is here and when plowing now, it just doesn't seem to have that get up and go. (though I do have 900 lbs in the back all the time for the ballast of 1000 lbs plow) Thanks.