With 4L80 Transmission

Throttle Position Sensor Circuit:

CIRCUIT DESCRIPTION
The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle blade. Signal voltage will vary from about .5 volt at idle to over 4.0 volts at Wide Open Throttle (WOT).

The TPS signal is one of the most important inputs used by the PCM/TCM for transmission control and for most of the PCM/TCM control outputs.

Code 22. 1991 Models w/diesel engine:

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

1. Code 22 will set if:
^ Engine running.
^ TPS signal voltage is less than about .2 volt for 1 second.

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

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


DIAGNOSTIC AIDS
A "Scan" tool reads throttle position in volts and should read about .45 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 Wide Open Throttle (WOT).

An open or short to ground in CKT 416 or CKT 417 will result in a Code 22.


"Scan" TPS while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from below 1.25 volts when throttle was closed, to over 4.0 volts when throttle is held at Wide Open Throttle (WOT) position.