P2138-ACCELERATOR PEDAL POSITION SENSOR 1/2 CORRELATION

For a complete wiring diagram Refer to Section 8W.

When Monitored:
With the ignition on and no APPS No.1 and APPS No.2 DTC present.
Set Condition:
APPS values No.1 and No.2 are not coherent. Idle is additionally forced when the brake pedal is pressed or failed. Acceleration rate and Engine output are limited. One trip fault and the code will set within 5 seconds. ETC light is flashing.

Possible Causes

EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT

EXCESSIVE RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT

EXCESSIVE RESISTANCE IN THE (K167) APP RETURN 1 CIRCUIT

EXCESSIVE RESISTANCE IN THE (K400) APP RETURN 2 CIRCUIT

EXCESSIVE RESISTANCE IN THE (K23) APP SIGNAL 1 CIRCUIT

EXCESSIVE RESISTANCE IN THE (K29) APP SIGNAL 2 CIRCUIT

APP SENSOR

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1. ACTIVE DTC

NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.

Ignition on, engine not running.
With a scan tool, select View DTCs.

NOTE: Repair any other 5-Volt Supply or APPS High and Low DTCs before diagnosing P2138.

Is the DTC Active at this time?

Yes

Go To 2

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

2. EXCESSIVE RESISTANCE IN THE (K23) APP SIGNAL 1 CIRCUIT

Turn the ignition off.
Disconnect the C3 harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.

Using a voltmeter perform a voltage drop test. Backprobe the (K23) APP Signal 1 circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

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 can result in personal injury or death.

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

Is the voltage below 0.5 of a volt?

Yes

Go To 3

Repair the excessive resistance in the (K23) APP Signal 1 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3. EXCESSIVE RESISTANCE IN THE (K167) RETURN 1 CIRCUIT

Turn the ignition off.
Move the voltmeter leads to backprobe the (K167) APP Return 1 circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

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

Is the voltage below 0.5 of a volt?

Yes

Go To 4

Repair the excessive resistance in the (K167) APP Return 1 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

4. EXCESSIVE RESISTANCE IN THE (K29) APP SIGNAL 2 CIRCUIT

Turn the ignition off.
Move the voltmeter leads to backprobe the (K29) APP Signal 2 circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

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

Is the voltage below 0.5 of a volt?

Yes

Go To 5

Repair the excessive resistance in the (K29) APP Signal 2 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

5. EXCESSIVE RESISTANCE IN THE (K400) APP RETURN 2 CIRCUIT

Turn the ignition off.
Move the voltmeter leads to backprobe the (K400) APP Return 2 circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

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

Is the voltage below 0.5 of a volt?

Yes

Go To 6

Repair the excessive resistance in the (K400) APP Return 2 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6. EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT

Turn the Ignition off.
Remove special tool #8815 from the C3 PCM harness connector and Re-Connect the C3 PCM harness connector to the PCM.
Disconnect the C2 PCM harness connector to install special tool #8815 and #8815-1.
Using a voltmeter perform a voltage drop test. Backprobe the (F855) 5-volt Supply circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

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

Is the voltage below 0.5 of a volt?

Yes

Go To 7

Repair the excessive resistance in the (F855) 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7. EXCESSIVE RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT

Turn the Ignition off.
Remove special tool #8815 from the C2 PCM harness connector and Re-Connect the C2 PCM harness connector to the PCM.
Disconnect the C1 PCM harness connector to install special tool #8815 and #8815-1.
Using a voltmeter perform a voltage drop test. Backprobe the (F856) 5-volt Supply circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

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

Is the voltage below 0.5 of a volt?

Yes

Go To 8

Repair the excessive resistance in the (F856) 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

8. CHECKING APPS NO.1 AND NO.2 WITH A LAB SCOPE

Ignition on, engine not running.
Set up a lab scope in a way that you can view two graphs simultaneously.
Backprobe (K23) APP Signal 1 circuit using Channel 1 at the APP Sensor harness connector.
Backprobe (K29) APP Signal 2 circuit using Channel 2 at the APP Sensor harness connector.
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 APP Sensor Assembly per Service Information. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No
Go To 9
9. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

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. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)