P0122

DTC P0122 Throttle Position (TP) Sensor Circuit Low (Signal Voltage Low):

Throttle Position (TP) Sensor Circuit:

Circuit Description
The Throttle Position (TP) sensor provides a voltage signal which changes relative to the throttle blade angle. Signal voltage will vary from about .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 VCM for fuel control and for most of the VCM control outputs. Every time voltage drops below 1.25 volts and stops, the VCM assumes this value as 0 throttle angle and measures percent throttle from this point on.

DTC P0122 Will Set When
TP sensor voltage is less than .2 volts.

Action Taken (VCM will default to)
TP 19%. NOTE: Tech 1 scan tool will not indicate default value.

DTC P0122 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 Fuse #9 (ECM B) fuse is removed for 10 seconds.

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

1. If TP signal is less than .2 volt, then the fault is present.

2. Simulates DTC P0123: (high voltage) - If the VCM recognizes the high signal voltage, the VCM and wiring are OK.

3. The VCM recognizes the voltage as over 4 volts, indicating that CKT 417 and the VCM are OK.

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

5. This step checks for CKT 416 open, shorted to ground, or a poor connection or faulty VCM.

Diagnostic Aids
A Tech 1 scan tool reads throttle position in volts. Should read about .45 to .85 volt with throttle closed and ignition "ON" or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).

An open or short to ground in CKTs 416 or 417 will result in a DTC P0122. Refer to "Intermittents." - Intermittent Malfunctions

Scan TP signal 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 4.5 volts (4500 mV) when throttle is held at Wide Open Throttle (WOT) position.