For the longest time i have had issues with my TPS. checked and replaced everything and the problem still haunts me. Today I had a possible breakthrough. For the first time ever the trouble code 15 came up. 22 and 21 would come up all the time for the TPS but never 15 which is for the coolant temp. sensor. I check my wire diagram and they share a common ground to the computer. They are also spliced with the IAT sesnor. Does anyone know where the three come together? Also i was tugging one of the grounds, not very hard, and the TPS ground came unconnected from the TPS. would a loose ground at the TPS cause the code 15 when the ground is spliced with the TPS? sorry so long. any help is much appreciated. thanks.

Sounds like you're chasing a short/break in your ground

Commons are difficult to place as they move from harness to harness, even in the same year. Ive seen them move 12" between two identical harnesses

Its odd that a single break would leave only two sensors in-op. Ground commons usually involve 2-4 sensors and are ALWAYS linked together as well as linking up for a block ground at the rear of one of the cyl heads. This is so you can break one ground, lets say to the head, and you will not lose grounding function as the common still has a jumper to the next common which goes to the head

Make sense?

If worse comes to worst, you can always run a new ground wire for both sensors to a new common, to a new end point and then tuck them into the loom

thanks, what side of the firewall do the grounds to the ECM go through? pass or drive?

Like I said, all grounds are connected. The ECM ones go thru the hole behind the fender up to the cyl heads and then back to the C100

i realize all grounds are supposed to be connected but i think somewhere i have a loose ground and was wondering where the multiple splice locations might be for those sensors. thanks.