Powertrain Controls - ECM/PCM

Code Chart 22:

TPS Circuit:

CIRCUIT DESCRIPTION:
The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle opening. Signal voltage will vary from 0.2-.74 volt at idle to above 4.0 volts at wide open throttle (WOT).

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

DTC 22 will set if:

^ The ignition key is "ON."
^ TP sensor signal voltage is less than 0.2 volts for 4 seconds.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. With the throttle closed and ignition "ON" TP sensor voltage should read 0.2 to 0.74 volts.

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

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

NOTE: If DTC 22 is set, the ECM will use a fail-soft value for TP sensor of about 3% throttle angle. The scan tool will continue to display actual sensor value.

DIAGNOSTIC AIDS:
Scan tool reads throttle position in volts. Voltage should increase at a steady reate as throttle is moved toward wide open throttle. the scan tool also displays throttle angle: 0%=closed throttle and 100%=WOT.

Check For:

^ Poor Connection or Damaged Harness Inspect ECM harness connectors for backed out terminal "YF13" or "BA4," improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.
^ Intermittent Test. If connections and harness check OK, monitor TP sensor voltage while moving related connectors and wiring harness. If the failure is induced, the display will change. This may help to isolate the location of the malfunction.
^ TP sensor Scaling. Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from .2-.74 volt when throttle is closed to over 4 volts when throttle is held at wide open throttle position.