Powertrain Controls - ECM/PCM

Code 22 Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION:

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.6 at idle to about 5 volts at Wide Open Throttle (WOT). The TPS signal is one of the most important inputs used by the Electronic Control Module (ECM) for fuel control and for most of the ECM control outputs.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Code 22 will set if TPS signal voltage is less than about 0.23 volts.

^ The TPS has an auto range zeroing feature. If the voltage reading is within the range of about 0.3 volts to 0.9 volts, the ECM will use that value as closed throttle. If the voltage reading is out of the auto zero range at closed throttle cable or damaged linkage. If good, continue with diagnosis.

2. Simulates Code 21 (high voltage). If the ECM recognizes the high signal voltage the ECM and wiring are OK.

3. This simulates a high signal voltage to check for an open in CKT 417.

DIAGNOSTIC AIDS:

A "Scan" tool reads throttle position in volts. Should read between 0.3 and 0.9 volts with throttle closed and ignition on or at idle. Voltage should increase at a steady rate as throttle is moved toward WOT. An open or short to ground in CKT 474 or CKT 417 will result in a Code 21, Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.