1993 f150 302 v8 2wd e4od

Brand new rebuilt tranny and now its shifting bad after 1300 miles or so. Made me think that my NEW TPS was bad so I ran codes. I believe I got code 63 low tp voltage. Ok. So I check tps and if I remember right I get somewhere between .9 and 1.5 v and moving throttle the numbers decrease smoothly. So I check 5v power from ecu to tps and get 1.7. It should be 4.5-5.0. When I move around probing wires in there sometimes I can hear a slight "click" and a slight drop in voltage to like 1.63. The goes back up to 1.7. Now I fear ecu bad or short in wiring.....NEED HELP I am not good w electrical so I really need a basic walkthrough to see if we can figure this out. I am also afraid I fried my new tranny. What a mess.

 

Any ideas why I am getting 1.7 v instead of 5???

 

Real stumper here with the throttle position sensor huh? Maybe if I break down what I did someone will understand?

Probe black wire w/ multimeter positive, negative on battery with key in on pos. Read I think 1.4 or so.

Probed red wire of TPS w/ positive multimeter set on DC w/ ground to battery. Read 1.7. Should be 5v right???

Any ideas here??? Is my cpu bad? Anyone know about these throttle position sensors?

 

I'd check for corrosion and shorts in the wiring first at the tps harness and pcm. You should be getting close to 5v at WOT. I think the resistance from the top pin and the middle pin is supposed to be 5 ohms or so on the tps.

 

Oh wait, I should be getting 5v at wot? So at closed throttle is what I measured. I will try again at wot. But I did get code 63 and this does feel like how an aod would feel with a misadjusted tv cable.

 

Yup voltage increases as you open up the throttle, the only thing that shows up for me to cause code 63 would be improperly inserted TPS, damaged, open or grounded harness and faulty PCM.

So I would start with checking the harness itself, check for open lines and the PCM harness itself. Otherwise it may be a faulty TPS but you will have to do more testing first.

But did you remember to disconnect the battery cable when you installed your new one and did you re-install it at its same position?

 

Yeah its installed correctly, batt was disconnected. Just so we are on the same page, the voltage I am referring to is the 5 volt power from pcm, the red wire. I should get 5 I get 1.7. I thought that was always 5 regardless of throttle position. Now the voltage on the black wire was 1.4 and decreased as I opened the throttle (to like .7 I think). I'll get numbers again tomorrow and post, I got no time to do it today.

 

Problem Solved Good Nuff.....

Here's what happened FYI. I probed wrong wire because guide I used was wrong. The green wire is the one to get the reading on the TPS to PCM. I replaced TPS and set it at exactly .99v. Also, I was actually getting 5.08v from PCM. Everything seems to run ok now or good nuff. Rebuilt tranny shifts ok, not as smooth as that first week, but no problems.

 

Have you taken it(tps) off to do any type of work on your engine?

 

No. The only times I ever had the TPS off was the 2 times I replaced it. I just pulled throttle body to do it. Why?