I replaced my tps with an ac delco on an 87 iroc, 350 tpi. Set at .58V. On a 52 mm BBK TB the max voltage at WOT is 2.0 V. Shouldn't it be close to 5?

The blades are fully opening and the voltage increases in a linear fashion and no codes. Is it a bad sensor?

Thanks for your replies.

 

I replaced my tps with an ac delco on an 87 iroc, 350 tpi. Set at .58V. On a 52 mm BBK TB the max voltage at WOT is 2.0 V. Shouldn't it be close to 5?

The blades are fully opening and the voltage increases in a linear fashion and no codes. Is it a bad sensor?


1. Be certain tha the throttle plates are fully closed before adjusting the TPS voltage. This may require you to disconnect the throttle cable from the pedal, the cruise control cable, and the TV cable to the transmission (if equipped). Make sure the minimum air position is set correctly so the throttles are closed almost fully.

2. Ascertain that the supply voltage to the TPs is 5.0 VDC ± 0.15VDC. That means you should be able to meter between 4.85 and 5.15VDC between the black and gray wires ('A' and 'C' connector terminals) at the TPS. If the reference voltage is low, you have a problem with the wiring harness or (less likely) the 5V supply from the ECM.

3. Meter the TPS output voltage between the black and blue wires (negative and positive, respectively) at the closed throttle position. DO NOT use an engine ground for a measurement reference. Set iit as close to 0.54VDC as practical. Manually operate the throttle bellcrank to the WOT position. You should measure at least 4.0VDC at that position.

 

Thanks for the quick reply Vader. It is the sensor, I borrowed one and it shows 4.2 V at WOT.

BSW

 

That's easy then.