TPS base resistance?

[barneyhyphen]

Took off the TPS and measured resistance (OHMS) between pins A & B which showed as 780. Manually rotated the center (as the butterfly would do) and resistance increased very uniformly.

Did same measurements on a new one out of the box but it's base resistance was 520.

Is this important? Thanks.

BH

 

[2000StreetRod]

potentiometer

The TPS is merely a potentiometer (variable resistor). The supply voltage (about 5 volts) is a applied across the entire potentiometer. The voltage sent to the PCM is the wiper resistance divided by the total resistance times the applied voltage. To determine if your replacement TPS differs from stock you'll have to measure the total resistance and compare the ratios (i.e. 780/3900=0.2*5.0=1.0 volts and 520/2600=0.2*5.0=1.0 volts). The PCM measures the TPS output voltage at ignition turn on and assumes it to be for closed throttle. Because of this, minor differences in closed throttle voltages do not matter. The PCM periodically checks for a lower voltage and if it finds one makes that the new closed throttle value. See Ford Explorer - Ranger TPS Test Procedure

 

[barneyhyphen]

Thank you 2000StreetRod. Very full explanation. Turns out I had a VERY much simpler problem/resolution so didn't need to replace the TPS.

BH