P1122

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Throttle Position (TP) sensor provides a voltage signal which changes relative to the throttle blade angle. The signal voltage vanes from about 0.5 volt at idle to about 4.0 volts at Wide Open Throttle (WOT).

The VCM uses the TP signal, one of the most important inputs, for fuel control and for most of the VCM control outputs.

Each time the voltage drops below 1.25 volts and stops, the VCM assumes this value as the 0 throttle angle, and the VCM measures the percent throttle from this point on. The DTC P0123 is a type A DTC.

The CONDITIONS FOR SETTING THE DTC

The engine is running.

ACTION TAKEN WHEN THE DTC SETS

The VCM stores the DTC to the History if the VCM detects an intermittent problem.

CONDITIONS FOR CLEARING THE MIL/DTC

^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle.

^ Use the scan tool Clear Information function.

^ Disconnect the VCM battery teed for 30 seconds.

DIAGNOSTIC AIDS

The scan tool reads throttle position in volts. The TP should read about 0.45 to 0.85 volts with the throttle closed and the ignition ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward Wide Open Throttle (WOT).

An open or short to ground in the 5 volt reference circuit or the TP sensor signal circuit results in a DTC P0122.

Refer to the Symptoms. Testing and Inspection

Scan the TP sensor signal while depressing the accelerator pedal with the engine stopped and the ignition ON. The 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 the Wide Open Throttle (WOT) position.

TEST DESCRIPTION

The numbers below refer to the step numbers in the diagnostic table.

2. If the TP signal is less than 0.2 volt, then the fault is present.

3. This step simulates the DTC P0123: (high voltage) If the VCM recognizes the high signal voltage, the VCM and the wiring are OK.

4. The VCM recognizes the voltage as over 4 volts, indicating that the TP sensor signal circuit and the VCM are OK.

5. This simulates a high signal voltage in order to check for an open in the TP sensor signal circuit.

6. This step checks the 5 volt reference circuit for an open, short to ground, or a poor connection or a faulty VCM.