Originally Posted by dustinb
I have two - an analog one and a digital one.
Ok, set your multimeter to measure resistance and unplug the TPS connector.
Then start measuring between each two of the 3 wires of the TPS.
You have 3 combinations to check.
The goal is to find the pair with constant resistance - the one that stays the exact same number (doesn't change) while you rotate the throttle body.
So, you found that pair - let's call those two wires X and Y and the constant resistance between them R (should be few KOhms).
One of those X and Y is the +5V the other one the Sensor Ground.
The third wire (the one which is left out - let's call it S) is the TPS signal.
What's left is which between X and Y is the +5V and which is the sensor ground. To find that out you have to measure between S and X or Y.
If the resistance between S and X is closer to 0 with the throttle closed, and rases up closer to R when you fully open the throttle. Then X is the Sensor Ground. Y is the +5V and if you measure between S and Y it will behave the opposite - the resistance between the two will be closer to R when the throttle is closed and decreases down to close to 0 when the throttle is fully opened.
Note tha above I said Sensor Ground - it means that TPS wire should go to the Sensor Ground pin of the ECU and not to its regular ground pins.
Ah, and also if your multimeter is auto switching units (between Ohms and KOhms) don forget that 100 Ohm on the display is a smaller resistance (closer to 0) that 5 KOhm. (1 KOhm = 1000 Ohm)
You can use both multimeters to back your findings up