DTC 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 0.29 at idle to about 4.8 volts at wide open throttle, and is nonadjustable. 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.

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

1. Code 22, will set if:
- Engine running
- TPS signal voltage is less than about 0.2 volt for 3 seconds.

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

3. TPS check: The TPS has an auto zeroing feature. If the voltage reading is within the range of 0.29 to 0.98 volt, the ECM will use that value as closed throttle. If the voltage reading is out of the auto zero range on an existing or replacement TPS, the TPS should be adjusted.

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

5. CKTs 416 and 474 share a common 5 volts buffered reference signal. If either of these circuits is shorted to ground, Code 22 will set. To determine if the Manifold Absolute Pressure (MAP) sensor is causing the 22 problem, disconnect it to see if Code 22 resets. Be sure TPS is connected and clear codes before testing.

DIAGNOSTIC AIDS:
- A "Scan" tool reads throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).
- Also, some "Scan" tools will read throttle angle. 0% = closed throttle, 100% = WOT
- An open, or short to ground, in CKTs 416 or 417 will result in a Code 22. Also, a short to ground, in CKT 474, will result in a Code 22.
- Refer to "Diagnosis by Symptoms / Intermittent Condition Diagnosis" - Intermittent Malfunctions