Powertrain Controls - ECM/PCM

Throttle Position Sensor Wiring Diagram:

Circuit Description:

The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.5 at idle to about 4.8 volts at Wide Open Throttle (WOT).

The TP sensor signal is one of the most important inputs used by the ECM for fuel control and for many of the ECM control outputs.


Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. DTC 21 will set if:

^ TP sensor signal voltage is greater than 2.5 volts.
^ Engine at idle (less than 12 grams per second calculated air flow).
^ All conditions met for 3 seconds.

OR

^ TP sensor voltage over 4.8 volts with ignition "ON".

2. With the TP sensor disconnected, the TP sensor voltage should go low, if the ECM and wiring are OK.

3. Probing CKT 470 with a test light checks the 5 volt return circuit. Faulty sensor ground circuit will cause a DTC 21.

Diagnostic Aids:

A scan tool reads throttle position in volts and percentage of throttle blade opening.

Scan the TP sensor while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from about 0.5 volt when throttle was closed, to about 4.8 volts when throttle is held at Wide Open Throttle (WOT) position.

An open in CKT 470 will result in a DTC 21. - Intermittent Malfunctions