| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. |
Circuit Description
The accelerator pedal position sensor is a 2 variable resistor sensor that monitors throttle opening and accelerator pedal position sensor malfunction. Accelerator pedal position sensor determines vehicle accelerator pedal position. ECM controls throttle motor and electromagnetic clutch based on signal from accelerator pedal position sensor. If DTC P1120 is set, ECM shuts down power to throttle control motor and electromagnetic clutch.
DTC P1120 is set when ECM consistently detects .2 volt or less, or 4.8 volts or more from VPA circuit, or .5 volt or less from VPA2 circuit for 2 seconds. DTC P1120 is also set when ECM consistently detects .2 volt or more and 1.8 volts or less from VPA circuit, and 4.97 volts or more from VPA2 circuit for 2 seconds.
DTC P1120 is also set when ECM consistently detects .2 volt or less from VPA circuit and 1.5 volts or less from VPA2 circuit for .4 second. DTC P1120 is also set when ECM consistently detects .2 volt or less from VPA or VPA2 circuit for 2 seconds. Possible causes are
- Open or short in accelerator pedal position sensor circuit.
- Faulty accelerator pedal position sensor.
- Faulty ECM.
Note. If DTCs P0110, P0115, P0120, P0450 and P1120 are output together, inspect ECM ground circuit(s) for an open. Repair as necessary. See WIRING DIAGRAMS article.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.