DTC 21

CIRCUIT DESCRIPTION
The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.5 at idle to 4.5 volts at wide open throttle.

The TPS signal is one of the most important inputs used by the ECM for fuel control and for most of the Engine Control Module (ECM) control Outputs.

The back-up mode signal is used only for calibrating fuel delivery in the ECM back-up mode.

Code 21 will set if:
^ Engine is running.
^ TPS signal voltage is greater than 2.5 volts.
^ Air flow in grams/second is less than 12 GM/sec.
^ All conditions met for 3 seconds.
OR
^ TPS signal voltage over 4.5 volts with ignition "on" or engine running.


CHART TEST DESCRIPTION
1. Confirms code 21, and that fault is present.

2. Simulates Code 22: If the ECM recognizes the high signal voltage and sets Code 22 the ECM and wiring are OK.