Hello!

So I just recently bought a 98 Corvette engine from eBay, I got the ECM flashed from LT1swap great guy by the way and when finally I got the car running on my engine stand I was not getting any throttle response. I troubleshot all I could, I checked for voltage on 5 Volts which is the black/yellow wire and believe a white wire. On the schematic is says there's a dark green wire that is ground and I check for ohms to get a 0 reading for ground but I don't get a reading at all so I'm assuming that I have no ground coming from the TAC module. Before I get asked about the TAC module when I purchased the engine it didn't come with the TAC module and pedal assembly the seller sold it apart so I had to spend another 300 dollars to buy it from the guy which he said it belonged to the Corvette originally, so I'm being a bit skeptical about it. I'm coming to a conclusion that I may either have a bad TAC module or possibly the wrong the one. I mean I even had to buy the cable that goes from pedal to the TAC module I just don't think that, THAT is the problem unless I'm wrong. I need help with this and wonder if anyone else has had this same issue with theirs. I've looked everywhere for answers and all I get directed to is for all other engines except a 98 specific TPS issue with a 6 wire TPS. Oh and when I put ignition power and the relays click as soon as I connect ignition I hear a sound come from the TPS like it's getting power, just no response from the Pedal. I would really appreciate any info. Thanks!

 

Moved to C5 Tech.

 

I believe my wiring for my 2001 should be the same as your ‘98. The 6 wire TPS consists of 2 ea. 5 volt reference wires, 2 signal wires, and 2 low reference wires (ground)...first off grounds are NOT checked using resistance !!...loaded circuit testing is the only way to test !!...the TPS consists of 2 separate potentiometers...to test the TPS circuit you must back probe each signal wire (dark blue and pink) with key on...you check voltage with your foot off the gas and WOT...here are the voltages you should see at both throttle angles...TPS 1 goes from a low to high voltage and TPS goes the opposite...is this what you see ???

 

I apologize that it has taken me this long to answer. So I'm checking it as we speak and by using my multimeter I checked the grounds, which is white wire and purple wire and I am getting ground to the plug at TPS. I have the "key ignition" to on and I dont get any voltage reading from the pink wire but I do get a .06 volts from the dark blue wire. I press on the pedal give it WOT and no change in voltage reading. Could it be my tac module that it is not sending a signal to the TPS?

 

OK, first disconnect the TPS harness...with key ON probe the yellow/black and dark green...you should see 5 volts on EACH of those wires...if not let us know...if OK now plug in the harness connector...you should see around 1.09 volts on the dark blue wire and 3.97 volts on the pink...YOU MUST BACK PROBE THOSE WIRES TO SEE THOSE VOLTAGES...how did you back probe these 2 wires ???...you won’t see that with the connector unplugged...these readings must be done with key ON !!...when you push the accelerator down those 2 voltages reading should go high (dark blue) and low (pink).

 

Ok... So I used a Bobby pin I scrapped off all of paint of off it and backed probed yellow/black and dark green in which I did get a 5V reading. I backed probed pink and I got 3.06V and 0.91V on dark blue. When I depressed on the pedal I don't get a drop or rise from any of the pink or dark blue wire. I've checked the voltage on my battery and I do have 12.16V so battery has charge. One thing I did notice is that I would turn key off and back on, back probed pink wire and as soon as I would check for voltage the throttle blade would jump but still no response from the pedal.

 

I had to read your initial post and not knowing if you have the correct TAC module or APP Sensor installed I would not be able to give you an answer to your issue !!

 

From the research I've done I've heard that the Corvette tac module is all plastic with no metal on it. So I'm assuming that I have the correct tac module and from comparing the pictures I also have the correct pedal for it. From what it looks like, but considering that you have given me a great amount of troubleshooting I'm coming to a conclusion that it could be either A: TAC module or B: APP so since there's no signal being sent to the TPS I'm gonna try and go with what cheap first and that's the APP and if that doesn't work then I guess I'll just get a new TAC module. I appreciate the help regardless I learned something either way.

This is what it looks like.