sean lawrence
Member
- Joined
- Jan 13, 2013
- Messages
- 185
I have a question for you that no one can seem to answer or can even attempt to answer and I am just at a stand still because I know the local mechanics will have no idea and will waste my time. I do all of my work and always have and have owned a mechanics shop for over 15 years. my question is I have went through 3 tps sensors all aftermarket and all of them will only go to around 3 volts when there supposed to go to 4.6 volts set correctly at wot but should be capable of 4.9 volts or so. why is it only going to 3 volts at wot? also that's just turning the arm on the tps to wot with the tps off the throttlebody eliminating the throttle cable, detent cable, cruise control cable and carpet issues that usually prevent the tps from going to wot. I finally got the correct tps sensor and that was hard to find gm part# 19187340 and I installed it and guess what it will still will not go above 3 volts at wot off or on the throttlebody. I then went to the wiring diagram and traced the tps wires back to the ecm. the grey wire is the 5 volt reference and its putting out 5 volts which is correct and it does not drop off voltage with tps plugged in or not and it stays 5 volts no matter what the tps arm is turned to, and that's what its supposed to do. ok on to the blue wire the return signal for the tps, just for the sake of the wire could be shorted out in the harness I unpinned the blue wire from the ecm which also eliminates back voltage if something is messed up with my ecm which I doubt, but I might as well check since I have done everything so I tested the blue wire from the tps at the ecm wherei unpinned it from the ecm and I still had the 3 volts at wot. next I unplugged the tps and looped the grey wire at the tps plug to the blue wire so I can make sure that wire was not shorted and I had a the full 5 volts like I should at wot. last I checked continuity for the black ground wire and it gave me a beep but kind of a high reading so I thought maybe a shorted ground wire in the harness so I back probed the ground and hooked it straight to the neg battery side to eliminate a bad ground wire. hooked it all back up and tested and still only 3 volts at wot. I really thought the aftermarket tps sensor was the problem but after 3 aftermarket tps showing the same and one factory tps straight out of the box from gm showing the same how could it be the tps? if all the wiring is good what else is there do check? I don't understand how if you have 5 volts reference why it will not let the 5 volts pass through the tps and to the return wire from the tps? because the tps regulates the voltage through the tps arm and its position soyou would think bad tps but with four tps sensors all saying the same how could it be the tps? I am really confused on this one has anyone ever had this problem? and what should I do next? thanks, sean
