2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P2138-ACCELERATOR PEDAL POSITION SENSOR 1/2 CORRELATION

P2138-ACCELERATOR PEDAL POSITION SENSOR 1/2 CORRELATION

For a complete wiring diagram, refer to the Wiring Information.

When Monitored:
With the ignition on, battery voltage greater than 10.4 Volts, and no APPS 1 and APPS 2 DTCs present.
Set Condition:
The Powertrain Control Module (PCM) detects that the correlation between APPS 1 and APPS 2 is not plausible. Idle may be affected when the brake pedal is pressed or if a brake switch circuit error is present. Acceleration rate and engine output are limited. One trip fault and the code will set within five seconds. ETC light is flashing.

POSSIBLE CAUSES
(K852) 5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE
(K23) APP SIGNAL 1 CIRCUIT OPEN OR HIGH RESISTANCE
(K167) APP SENSOR GROUND 1 CIRCUIT OPEN OR HIGH RESISTANCE
(K854) 5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE
(K29) APP SIGNAL 2 CIRCUIT OPEN OR HIGH RESISTANCE
(K400) APP SENSOR GROUND 2 CIRCUIT OPEN OR HIGH RESISTANCE
ACCELERATOR PEDAL POSITION SENSOR
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

1. DTC IS ACTIVE

NOTE: Diagnose and repair any APPS, system voltage, or sensor supply voltage DTCs before continuing with this test.

1.	Start the engine and allow it to reach normal operating temperature.

WARNING:

When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2.	With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go To 2

No

Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

2. (K852) 5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE

1.	Turn the ignition off.

2.	Disconnect the Accelerator Pedal Position Sensor harness connector.

3.	Disconnect the Powertrain Control Module (PCM) C1 harness connector.

4.	Measure the resistance of the (K852) 5-Volt Supply circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 3

No

Repair the (K852) 5-Volt Supply circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

3. (K23) APP SENSOR SIGNAL 1 CIRCUIT OPEN OR HIGH RESISTANCE

1.	Measure the resistance of the (K23) APP Sensor Signal 1 circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 4

No

Repair the (K23) APP Sensor ignal 1 circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

4. (K167) APP SENSOR GROUND 1 CIRCUIT OPEN OR HIGH RESISTANCE

1.	Measure the resistance of the (K167) APP Sensor Ground 1 circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 5

No

Repair the (K167) APP Sensor Ground 1 circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

5. (K854) 5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE

1.	Measure the resistance of the (K854) 5 Volt Supply circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 6

No

Repair the (K854) 5 Volt Supply circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

6. (K29) APP SIGNAL 2 CIRCUIT OPEN OR HIGH RESISTANCE

1.	Measure the resistance of the (K29) APP Signal 2 circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 7

No

Repair the (K29) APP Signal 2 circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

7. (K400) APP SENSOR GROUND 2 CIRCUIT OPEN OR HIGH RESISTANCE

1.	Measure the resistance of the (K400) APP Sensor Ground 2 circuit between the Accelerator Pedal Position Sensor harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 8

No

Repair the (K400) APP Sensor Ground 2 circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

8. ACCELERATOR PEDAL POSITION SENSOR

1.	Turn the ignition off.

2.	Connect the Accelerator Pedal Position Sensor harness connector.

3.	Connect the Powertrain Control Module (PCM) C1 harness connector.

4.	Turn the ignition on.

5.	Set up a lab scope to view two graphs simultaneously.

6.	Using one channel on the lab scope, backprobe the (K23) APP Signal 1 circuit at the APP Sensor harness connector.

7.	Using the other channel on the lab scope, backprobe the (K29) APP Signal 2 circuit at the APP Sensor harness connector.

8.	Slowly press and release the Accelerator Pedal while monitoring the lab scope screen.

Does the scope pattern show any missing or erratic signals?

Yes

Replace the Accelerator Pedal Position Sensor in accordance with the Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

Go To 9

9. POWERTRAIN CONTROL MODULE (PCM)

1.	Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Accelerator Pedal Position Sensor and the Powertrain Control Module (PCM).

2.	Look for any chafed, pierced, pinched, or partially broken wires.

3.	Look for broken, bent, pushed out or corroded terminals.

4.	Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.

5.	Look for the data to change or for the DTC to reset during the wiggle test.

6.	Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control - Removal) .
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).