TPS Circuit

The TPS and the MAP sensor share the 5 volt reference feed. The A/D converter on the 5 volt reference feed is used to detect whether the 5 volts is present or not. If the voltage is not there a “5v reference out of range”fault code. One possible cause of this fault is the 5 volt reference circuit being shorted to ground.

The ECM watches the A/D converter on the signal wire. If the voltage goes too close to 0v, then a “TPS voltage low”fault is set. If the voltage goes too close to 5v, then the ECMsets a “TPS voltage high”fault.

Remember, the fault codes are set by what voltage the ECM “sees”at the A/D converter. As an example, a TPS voltage low fault could be set by an open in the signal wire, a shorted signal wire, or an open in the 5 volt reference feed.

A good quick check of the TPS circuitry is to disconnect the TPSand with a voltmeter check from cavity A to a known good ground. If the voltmeter measures 5 volts, then measure between cavities A and B. If the voltmeter still reads 5 volts, then the sensor return is good. Then short the 5 volt reference into the signal wire and read TPS Volts with a scan tool. If the scan tool reads 5 volts, then the signal wire is good and the ECM can read the voltage with the A/D converter.