VStar650CL wrote: ↑
Fri Jan 15, 2021 9:31 pm
Three-pin TPS's are generally balance resistors (pots). Chances are the center pin is signal, with one end pin connecting to power and the other end pin connecting to ground. To confirm that, take ohm readings from center to end on both pins. Then rotate the sensor to the stop and take readings again. If resistance on one side increases after rotation and the other side decreases, then it's a plain-old potentiometer.
Alright, you're correct that the center is signal and that backs up what I thought about it already, thank you. If I label the pins from left to right with the sensor facing down as it sits in the 3rd photo then pins 1+2 sweep from 4300ohms to about 800 ohms, pins 2+3 sweep from about 700 ohms to about 4100 ohms. Pins 1+3 have a static resistance of 4700 ohms either way I probe it so I don't think there's any kind of diode inside I'll smoke. According to the intake manifold install guide I'm following in order to get everything read to install this table shows what I should be seeing between the pins of a Q45 TPS with that harness out the side of it.
How they laid it out is a bit confusing.
I'll try hooking up power and ground from an old PC power supply (easy 5V source) on pins 1+3 and see if the voltage on pin 2 sweeps like what my ECM is looking for, about .4 closed and about 4.6 full open which is roughly the same as a Q45 happily. If I don't get the sweep I need then I'll look for the correct sensor I guess and chock this up to a $90 learning experience to not buy things on eBay's mobile app because it makes seeing important information like the seller doesn't accept returns painfully obtuse. What's odd is that RockAuto also lists the same style sensor for a 91-94 Q45 but neither harness connector they sell for the same car fits this sensor. Someone somewhere screwed up a parts listing. https://www.rockauto.com/en/moreinfo.ph ... 2764&jsn=8