Powertrain Controls - ECM/PCM

DTC 22 Chart (PCM):

TP Sensor Circuit (PCM):

Circuit Description:
The Throttle Position (TP) Sensor provides a voltage signal that changes relative to the throttle blade angle. 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. On nonadjustable TP switches, each time voltage drops below 1.25 volts and stops, the PCM assumes this value is 0 throttle angle and measures percent throttle from this point on.

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

1. This step checks to see if Code 22 is the result of a hard failure or an intermittent condition. Code 22 will set if:

- Engine running.

- TP signal voltage is less than about 0.2 volts for 4 seconds.

2. Simulates Code 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 CKT 417.


Diagnostic Aids:
A Tech 1 "Scan" tool reads throttle position in volts. Should read about 0.5 to 1.25 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 code 22.

Refer to "Intermittents"

"Scan" TP 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.