Diagnostic Aids

NOTE: If this code IS NOT displayed during the third pass of diagnostic codes, it is an intermittent failure and cannot be diagnosed using this procedure. For an intermittent code, refer to NOTE ON INTERMITTENTS.

The ECM supplies a 5 volt signal to pin C (circuit 474) of the Throttle Position Sensor (TPS) and supplies a ground path to pin B (circuit 476-X). The TPS signal from pin A (circuit 417) is a variable voltage which is dependent on the throttle position.

Trouble Code 22 indicates that the voltage signal from the TPS is too low. This situation can be observed in engine data display as a "throttle angle" reading (parameter .0.1) of - 10 to -6 degrees at part throttle. Possible causes of this condition are:

A. A defective throttle position sensor.
B. Defective wiring, terminals, etc.
C. An ECM which is unable to process signals properly.

If the opposite condition (high TPS signal) is created, then the self-diagnostics can be used to detect this failure by displaying engine data parameter .0.1. With the opposite condition created parameter .0.1 should display a throttle angle" reading of 87 to 90 degrees. To create a high TPS signal, disconnect the TPS connector and jumper circuits 417 and 474 together. If the "throttle angle" reading is now 87 to 90 degrees, the fault must be improper mating of sensor terminals or a faulty TPS.
If the "throttle angle" reading is 86 degrees or less, measure the voltage on circuit 474. If the voltmeter reads 0 volts, then the throttle position sensor is not receiving 5 volts and circuit 474 must be repaired for an open or short to ground.
If the voltmeter reads 5 volts, then measure the voltage between circuits 474 and 417. If the voltage is 5 volts, check circuit 417 for a short to ground. If the wiring is OK, then the fault must be in the ECM connector or ECM itself.
If the voltmeter does not read 5 volts, then an open must exist in either the wiring harness or the ECM. If the "throttle angle" reading is stil1 86 degrees or less with circuits 474 and 417 jumpered together at the ECM, the fault must be in the ECM connector or ECM itself. If the reading is 87 to 90 degrees, then circuit 417 is open.