Powertrain Controls - ECM/PCM

Code 22 Chart:

Wiring Diagram For TPS:

CIRCUIT DESCRIPTION:

The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle blade angle. Signal voltage will vary from about 0.5 volts at idle, to about 5.0 volts at Wide Open Throttle (WOT). The TPS signal is one of the most important inputs used by the ECM for fuel control, and for most of the ECM controlled outputs.


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

1. This checks to see if a Code 22 is the result of a hard code failure or an intermittent problem.
A Code 22 will set under the following conditions:
a. Engine running.
b. TPS signal voltage is less than 0.2 volts for three seconds.

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

3. The TPS has an auto zeroing feature. If the voltage reading is within the range of 0.35 to 0.7 volts, the ECM uses that value as closed throttle. If the reading is out of the auto range with the throttle closed, check for a binding throttle cable or damaged linkage. If OK, replace TPS. See COMPONENT REPLACEMENT AND REPAIR PROCEDURES.

4. This simulates a high signal voltage in order to check for an open 417 circuit. The "Scan" tool will not read up to 5.0 volts, but the ECM should recognize the signal on circuit 417.


DIAGNOSTIC AIDS:

1. A "Scan" tool displays TPS in volts. Closed throttle voltage should be less than 1.25 volts, and the voltage value should increase at a steady rate as the throttle is opened with the ignition "ON" or engine idling.
2. An open or short to ground in circuits 416 or 417 will result in a Code 22. If a Code 22 is intermittent, see DIAGNOSIS BY SYMPTOM.