P2128
P2128-ACCELERATOR PEDAL POSITION SENSOR 2 CIRCUIT HIGH
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The throttle pedal produces two voltage signals proportional to the pedal movement. The primary signal varies between 0 and 5.0 Volts and the secondary signal varies between 0 and 2.5 Volts. The Powertrain Control Module (PCM) uses the two signals to validate throttle pedal position to control engine fueling. The PCM illuminates the MIL lamp and ETC light solid immediately after the diagnostic runs and fails. Acceleration rate and Engine output are limited. The PCM will turn off the MIL lamp after the diagnostic runs and passes in four consecutive drive cycles.
- When Monitored:
Any time the Powertrain Control Module is powered up.
- Set Condition:
When APP Sensor No.2 voltage is above 2.5 Volts for one second.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. APP SENSOR NO.2 VOLTAGE ABOVE 2.5 VOLTS
NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.
1. Ignition on, engine not running.
2. With a scan tool, read the APP Sensor No.2 voltage.
NOTE: Diagnose any 5-Volt Supply DTCs before continuing.
Is the voltage above 2.5 Volts?
Yes
- Go To 2
No
- Go To 8
2. CHECK THE ACCELERATOR PEDAL POSITION SENSOR
1. Turn the ignition off.
2. Disconnect the APP Sensor harness connector.
3. Ignition on, engine not running.
4. With a scan tool, monitor the Accelerator Pedal Position Sensor voltage.
Is the voltage above 0 Volts?
Yes
- Go To 3
No
- Replace the APP Sensor Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
3. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR A SHORT TO BATTERY
1. Turn the ignition off.
2. Disconnect the C2 PCM harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (K29) APP Sensor 2 Signal circuit in the APP Sensor harness connector.
Is the voltage above 0 Volts?
Yes
- Repair the (K29) APP Sensor 2 Signal circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 4
4. CHECK FOR THE (K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (F856) 5-Volt Supply circuit in the APP Sensor harness connector.
Is the resistance below 10k Ohms?
Yes
- Repair the short between the (K29) APP Sensor 2 Signal circuit and the (F856) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 5
5. CHECK FOR THE (K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT
1. Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (F855) 5-Volt Supply circuit in the APP Sensor harness connector.
Is the resistance below 10k Ohms?
Yes
- Repair the short between the (K29) APP Sensor 2 Signal circuit and the (F855) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 6
6. CHECK THE (K400) APP SENSOR 2 RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K400) APP Sensor 2 Return circuit from the APP Sensor harness connector to the C2 PCM harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 7
No
- Repair the (K400) APP Sensor 2 Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
7. POWERTRAIN CONTROL MODULE
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
8. APP SENSOR NO.2 SWEEP
1. Ignition on, engine not running.
2. With a scan tool, monitor the Accelerator Pedal Position Sensor voltage.
3. Slowly press the Accelerator Pedal down.
Does voltage start at approximately 0 Volts and go above 2.31 Volts with a smooth transition?
Yes
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test
No
- Replace the APP Sensor Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.