Powertrain Controls - ECM/PCM

DTC 22 Throttle Position Sensor Circuit (Signal Low):

Throttle Position (TP) Sensor Schematic:

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 at idle to about 4.5 volts at Wide Open Throttle (WOT).
The TP sensor signal is one of the most important inputs used by the Powertrain Control Module (PCM) for fuel control and for most of the PCM control outputs.

DIAGNOSTIC TROUBLE CODE (DTC) 22 WILL SET WHEN
TP sensor signal is less than 0.2 volt with engine running.

ACTION TAKEN (PCM will default to)
The PCM will determine fuel and air calculations using calibrated values from a default table (0.93V). The Malfunction Indicator Lamp (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.

DTC CHART 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 then the PCM and wiring are OK.
2. TP sensor check. The TP sensor has an "Auto Zeroing" feature. This means that the PCM has the ability to auto-zero the TP sensor voltage if it is below about 1.25 volts at idle. The PCM will use this value to be 0% throttle. The TP sensor is not adjustable. If the TP sensor voltage is out of the "Auto Zeroing Range," check for binding or sticking cruise control or throttle cables. If OK, replace the TP sensor.
3. This simulates a high signal voltage to check for an open CKT 417.
4. CKT 416 is a 5 volt buffered reference signal. If CKT 416 is shorted to ground, DTC 22 will set. To determine if the Manifold Absolute Pressure (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. Should read less than 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. Tech 1 will also display throttle angle. Key "ON" engine "OFF" Tech 1 will display less than 100% at WOT.
An open or short to ground in CKT 416 or CKT 417 will result in a DTC 22.

Refer to Intermittents under Computers and Control Systems/System Diagnosis/Diagnosis By Symptom. - Intermittent Malfunctions