Powertrain Controls - ECM/PCM

DTC 22 Chart:

Throttle Position Sensor Circuit:

Circuit Description:
The Throttle Position (TP) sensor provides a voltage signal to the PCM that increases as the throttle blade angle increases. This signal voltage will vary from approximately .5 volt at idle to 4.8 volts at Wide Open Throttle (WOT). The TP sensor is one of the most important inputs to the PCM for governing fuel control of the engine.

DTC 22 Will Set When:
TP sensor signal is less than .2 volt with engine running, and RPM greater than 400. Condition must be met for 3 seconds.

Action Taken (PCM will default to):
The PCM will determine fuel and air calculations using calibrated values from a default table. The transmission will have maximum line pressure, no TCC and no 4th gear in hot mode. The MIL will become illuminated.

DTC 22 Will Clear When:
A current DTC 22 will clear when a low signal voltage below the calibrated DTC 22 threshold is no longer detected. A history DTC 22 will clear after 50 consecutive ignition key cycles without a current DTC 22 being stored.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. Simulates DTC 21 (high voltage): If the PCM recognizes the high signal voltage, the PCM and wiring are OK.

2. TP sensor check: The TP sensor has an auto zeroing feature. If the voltage reading is within the range of 0.29 to 0.98 volt, the PCM will use that value as closed throttle. If the voltage reading is out of the auto zero range on an existing or replacement TP sensor, check for cruise control and throttle cables for being held open.

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

4. CKT 416 is a 5 volts buffered reference signal. If CKT 416 is shorted to ground, DTC 22 will set. To determine if the MAP sensor is causing the DTC 22 problem, disconnect it to see if DTC 22 resets. Be sure TP sensor is connected and clear DTC(s) before testing.

Diagnostic Aids:
A Tech 1 scan tool reads throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward 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 DTC 22.

Scan TP sensor while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from about .5 volt when throttle was closed, to about 4.8 volts when throttle is held at WOT position.

Also some scan tools will read: throttle angle 0% = closed throttle, 100% = wide open throttle.

If DTC 22 is set, check CKT 416 for faulty wiring or connections.

Refer to "Intermittents" in "Diagnosis By Symptom." - Intermittent Malfunctions