• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
---|---|---|---|---|---|
Accelerator Pedal Position (APP) Sensor 1 5-Volt Reference Circuit | P0641 | P2138 | P2120 | P0641 | -- |
Accelerator Pedal Position (APP) Sensor 2 5-Volt Reference Circuit | P0651 | P2138 | P2125 | P0651, P0190 | -- |
Accelerator Pedal Position (APP) Sensor 1 Signal | P2120 | P2138 | P2120 | P0641, P2120 | P2138 |
Accelerator Pedal Position (APP) Sensor 2 Signal | P2125 | P2138 | P2125 | P2125 | P2138 |
Accelerator Pedal Position (APP) Sensor 1 Low Reference | -- | P2138 | P2120 | -- | -- |
Accelerator Pedal Position (APP) Sensor 1 Low Reference | -- | P2138 | P2125 | -- | -- |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: The engine is operating at idle. Parameter Normal Range: APP Sensor 1 0.9-1.2 Volts Parameter Normal Range: APP Sensor 2 varies 0.45-0.62 Volts | |||
5-Volt Reference 1 | 0 Volts | 0 Volts | APP 1 2.08 Volts |
5-Volt Reference 2 | 0 Volts | 0 Volts | APP 2 0.86 Volts |
APP Sensor 1 Signal | 0 Volts | 0 Volts | 5 Volts |
APP Sensor 2 Signal | 0 Volts | 0 Volts | 5 Volts |
APP Sensor 1 Low Reference | -- | 5 Volts | -- |
APP Sensor 2 Low Reference | -- | 5 Volts | -- |
The accelerator pedal assembly contains two accelerator pedal position (APP) sensors. The APP sensors are mounted in the pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to the position of the accelerator pedal. The engine control module (ECM) supplies a separate 5-volt reference and low reference circuit for each of the APP sensors.
The APP sensor 1 signal voltage increases as the pedal is depressed, from approximately 1 volt at rest to above 4 volts when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 0.5 volts at rest to more than 2 volts with the accelerator pedal fully depressed.
• | The ignition is ON or the engine is operating. |
• | The DTCs run continuously once the above conditions are met. |
The APP sensor 1 voltage is less than 0.59 volts for more than 4 seconds.
The APP sensor 1 voltage is more than 4.62 volts for more than 4 seconds.
The APP sensor 2 voltage is less than 0.28 volts for more than 4 seconds.
The APP sensor 2 voltage is more than 2.32 volts for more than 4 seconds.
The ECM detects that the voltage difference between APP sensor 1 and 2 is more than a predetermined value.
DTCs P2120, P2125, and P2138 are Type C DTCs.
DTCs P2120, P2125, and P2138 are Type C DTCs.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
• | APP Sensor 1 low reference circuit terminal 4 |
• | APP Sensor 2 low reference circuit terminal 2 |
⇒ | If greater than the specified range, test the low reference circuit for a short to voltage, or an open/high resistance. If the circuits test normal, replace the ECM. |
Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.
• | APP Sensor 1 5-volt reference circuit terminal 5 |
• | APP Sensor 2 5-volt reference circuit terminal 6 |
⇒ | If less the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuits test normal, replace the ECM. |
⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuits test normal, replace the ECM. |
• | APP Sensor 1 signal circuit terminal 3 |
• | APP Sensor 2 signal circuit terminal 1 |
⇒ | If greater than the specified range, test the appropriate signal circuit for a short to voltage. If the circuits test normal, replace the ECM. |
⇒ | If less than the specified range, test the appropriate signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the ECM. |
⇒ | If both scan tool APP sensor parameters display greater than the specified range, test the signal circuits for being shorted together condition. If the circuits test normal, replace the ECM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for engine control module replacement, setup, and programming |