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Home >> Dodge or Ram Truck >> 2012 >> RAM 3500 Truck 2WD L6-6.7L DSL Turbo High Output >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P2127

P2127






P2127-ACCELERATOR PEDAL POSITION SENSOR 2 CIRCUIT LOW





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 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 the APP Sensor No.2 voltage is below 0.05 of a Volt for one second.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. CHECK THE APP SENSOR BELOW VOLTAGE

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.1 voltage.

NOTE: Sensor No. 2 is pulled low by the PCM as part of its system testing. This test happens a couple of times a second. So you can expect to see voltages close to zero occasionally with a normal sensor.

Is the voltage consistently below 0.05 Volts?

Yes

- Go To 2

No

- Go To 11

2. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT




1. Turn the ignition off.
2. Disconnect the APP Sensor harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (F856) 5-Volt Supply circuit in the APP Sensor harness connector.

Is the voltage between 4.65 and 5.36 Volts?

Yes

- Go To 3

No

- Go To 8

3. CHECK THE ACCELERATOR PEDAL POSITION SENSOR




1. Connect a jumper wire between the (F856) 5-Volt Supply circuit and the (K29) APP Sensor 2 Signal circuit in the Sensor harness connector.
2. With a scan tool, monitor the APP Sensor No.2 voltage.

Is the voltage between 4.65 and 5.36 Volts with the jumper wire installed?

Yes

- 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.

No

- Go To 4

4. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE

NOTE: Remove the jumper wire before continuing.

1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance of the (K29) APP Sensor 2 Signal circuit from the APP Sensor harness connector to the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the (K29) APP Sensor 2 Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (K29) APP Sensor 2 Signal circuit in the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the (K29) APP Sensor 2 Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 6

6. CHECK FOR THE (K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO THE (K400) APP SENSOR 2 RETURN CIRCUIT




1. Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (K400) Sensor 2 Return circuit in the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K400) APP Sensor 2 Return circuit and the (K29) APP Sensor 2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 7

7. CHECK FOR THE (K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO THE (K167) APP SENSOR 1 RETURN CIRCUIT




1. Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (K167) Sensor 1 Return circuit in the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K167) APP Sensor 1 Return circuit and the (K29) APP Sensor 2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 10

8. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the C2 PCM harness connector.
3. Measure the resistance of the (F856) 5-Volt Supply circuit between the APP Sensor harness connector to the C2 PCM harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 9

No

- Repair the (F856) 5-Volt Supply circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

9. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (F856) 5-Volt Supply circuit in the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the (F856) 5-Volt Supply circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 10

10. 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.

11. APP SENSOR SWEEP
1. Ignition on, engine not running.
2. With a scan tool, monitor the APP Sensor No.2 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.

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