I am located in buffalo NY and am looking for a guy that knows his **** when it comes to these truckws...I mean I have a dumb shifting problem that hasnt been explainable through this site twice now nothing wrong with the site just too **** complicated and I keep getting TPS is bad or grounds and both have been done along with new PCM and speed senors. I need someone to put heads together with me and figure this **** thign out its goin on 6 months no with an intermittent OD/ lockup shifting problem with cruise turning off too.

 

Its been an intense summer trying to figure this dang truck out and its a southern truck so corrosion isnt a huge issue either. I have run a ground from the TPS to the Batt, cleaned the terminals and ground, replaced the PCM, speed sensors on tranny and rear end, and swore alot this summer. A few people have told me that 5V is always supposed to be at the tranny but its not. I too the scan tool and marked down the voltage at the tranny from the TPS signal and it fluctuates with throttle. Mine says 5v all the time when it decides to screw up and it will not shift into OD and lockup because the transmission thinks its wide open throttle with 5V. Somewhere between the PCM and the tranny, something is telling or giving the TPS wire 5v. I don't even think the TPS gives off 5v as when I was wide open I wrote the voltage down and it was 3.9v So any takers this time???

 

the pcm sends the 5v ref to the tp, the tp then steps it down and varies according to throttle position generally from (.5lowest-4.5max) If you are seeing 5v measured for the tp value then you have an open circuit and should get a dtc pertaining to tp-v high. I would start with monitoring the tp-v while you or someone else monitors tp-v and start wiggling wires and connections, pay close attention to the tp connector and the wires going into the connectors. I have seen a couple with loose fitting pins, and one with a broke wire under the insulation

 

thanks alot jnicewan I was thinkin the same thing. I have the box on the truck and am going to wiggle the wires and check connections I have the factory service manuals so I can easily grab the pin for the tps and follow the wire.

 

So the pcm sends it to the apps, then the apps sends it down to the tranny? I thought the tops sent it to the pcm then that went to the tranny? hmmm now i got myself guessin. Yes i have a code saying TPs voltage high. But the tps reading at the engine controller is fine its the tps value at the tranny that has 5v all the time which led me to believe that the wiring to the tranny was screwy.

 

When this happens the cruise also stops turning on. So the high voltage must be keeping the cruise from coming on as well.

 

Cuz theres two TPs voltage references...one in engine modes which is working fine with throttle movement it increases and decreases voltage. The other at the tranny tho is a constant 5V

 

Ok so I have the wiring diagram right from the dealer manual in front of me.....It looks like the Apps sends a signal to the JTEC controller. That voltage that is read there is correct as it fluctuates with the gas pedal as it should. Now from the JTEC controller there is a secondary 5V supply that is sent out to the trans pressure solenoid. That is where it does not fluctuate as it is supposed to. When it works fine, it will read the same as the other apps signal does which tells the tranny when to shift into OD and lockup. When it is screwy it stays at 5V constant which fools the trannny into thinking it is wide open. That also sends a voltage signal to the speed control box which is shown on the diagram which would explain cruise not working when this happens. This is starting to make sense does anyone have any backing to support my issue? Any help is appreciated

 

So looked at the manual this weekend anyone that can give me the wire color that supplys the tranny with the tps signal so I can trace it?