Refer to the TPS info below. The grey PCM wire should be showing around five volts:
The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit. It is a potentiometer with one end connected to 5 volts from the ECM/PCM (Grey wire) and the other end to ECM/PCM earth (Black wire with Yellow stripe). A third (Blue) wire connects from a sliding contact in the TP sensor to the ECM/PCM allowing the ECM/PCM to measure the voltage from the TP sensor. As the throttle is moved (accelerator pedal moved), the output of the TP sensor changes. At a closed throttle position, the output of the TP sensor is below 1.25V. As the throttle valve opens, the output increases so that, at wide-open throttle, the output voltage should be about 4 volts.
By monitoring the output voltage from the TP sensor, the ECM/PCM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts of fuel from the injectors, and an unstable idle, because the ECM/PCM interprets the throttle is moving.
The TP sensor is not adjustable and there is not a set value for voltage at closed throttle because the actual voltage at closed throttle can vary from vehicle to vehicle due to tolerances. The ECM/PCM has a special program built into it that can adjust for the tolerances in the TP sensor voltage reading at idle. The ECM/PCM uses the reading at idle for the zero reading (0% throttle) so no adjustment is necessary. Even if the TP sensor voltage reading were to change for some reason, the TP sensor will still be 0% because the ECM/PCM will learn the new value and it will become the new closed throttle value to be used and no driveability complaint will be present because the ECM/PCM learned a new setting.A TP sensor circuit problem will set DTC 21 or DTC 22.If the internal spring in the TP sensor fails, the TP sensor will be stuck high. A sticking TP sensor should set DTC 19.
