DTC P2138

Circuit Description

The accelerator pedal position (APP) sensor 1 and APP sensor 2 are potentiometer type sensors, each with the following circuits:

A 5-volt reference circuit
A low reference circuit
A signal circuit

The control module provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 and the APP sensor 2 signal voltages are both low at rest and increase as the pedal is depressed. When the control module detects that the APP sensor 1 and the APP sensor 2 signal circuits are out of correlation, DTC P2138 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation

Conditions for Running the DTC

DTCs P2107 and P2108 are not set.
The ignition is in the CRANK or RUN position.
The ignition voltage is more than 5.23 volts.
The communication between the throttle actuator control (TAC) module and the powertrain control module (PCM) must be valid.

Conditions for Setting the DTC

The PCM detects that the difference between APP sensor 1 and APP sensor 2 is more than the predicted value.

Action Taken When the DTC Sets

The control module stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

A current DTC Last Test Failed clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
Clear the DTC with a scan tool.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views and Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	--	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Observe the DTC Information with a scan tool. Is DTC P0641 or P0651 also set?	--	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 3
3	Turn OFF the ignition. Disconnect the accelerator pedal position (APP) sensor electrical connector. Disconnect the throttle body harness connector. Measure the resistance of the following circuits for each of the APP sensors with a DMM: The low reference circuit The signal circuit The 5-volt reference circuit Is the resistance more than the specified value for any circuit?	5 ohms	Go to Step 7	Go to Step 4
4	Test the signal circuit of the APP sensor 1 for a short to the signal circuit of the APP sensor 2. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 9	Go to Step 5
5	Test for an intermittent and for a poor connection at the APP pedal assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 9	Go to Step 6
6	Test for an intermittent and for a poor connection at the throttle body harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 9	Go to Step 8
7	Repair the high resistance in the circuit that measured above the specified value. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 9	--
8	Replace the APP sensor. Refer to Accelerator Controls Pedal Replacement . Did you complete the replacement?	--	Go to Step 9	--
9	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	--	Go to Step 2	Go to Step 10
10	Important Be aware that repairing one individual condition may correct more than one DTC. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	--	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK