Powertrain Control Module - PCM

Diagnostic Trouble Code 22:

TP Sensor Circuit:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about 0.5 volt at idle to about 4.0 volts at Wide Open Throttle (WOT).

The TP signal is one of the most important inputs used by the PCM for fuel control and for most of the PCM control outputs.

DTC 22 WILL SET WHEN
^ Engine running.
^ TP signal voltage is less than 0.15 volts for more than 4 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
The Malfunction Indicator Lamp (MIL) will illuminate, transmission TCC will not apply, high transmission line pressure, harsh shifts, fixed shift points and no fourth gear in hot mode.

DTC 22 WILL CLEAR WHEN
Conditions for fault are no longer present and Tech 1 "clear DTCs" function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and battery feed voltage is removed for 10 seconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Verifies TP signal display.

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

3. This step determines a poor connection or faulty TP sensor.

4. This simulates a high signal voltage to check for an open in TP sensor signal circuit.

DIAGNOSTIC AIDS
A Tech 1 scan tool reads throttle position in volts and should read about 0.5 to 1.25 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 416 or 417 will result in a DTC 22.

Refer to Diagnosis By Symptom / Intermittents - Intermittent Malfunctions

Scan TP sensor while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from below 1.25 volts (1250 mV) when throttle was closed, to over 4.0 volts (4000 mV) when throttle is held at WOT position.