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 CausesEXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUITEXCESSIVE RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUITEXCESSIVE RESISTANCE IN THE (K167) APP RETURN 1 CIRCUITEXCESSIVE RESISTANCE IN THE (K400) APP RETURN 2 CIRCUITEXCESSIVE RESISTANCE IN THE (K23) APP SIGNAL 1 CIRCUITEXCESSIVE RESISTANCE IN THE (K29) APP SIGNAL 2 CIRCUITAPP SENSORPCMAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).1. ACTIVE DTCWhen 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.Repair any other 5-Volt Supply or APPS High and Low DTCs before diagnosing P2138.Is the DTC Active at this time?YesGo To 2NoRefer 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 CIRCUITTurn the ignition off.Disconnect the C3 harness connector.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.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?YesGo To 3NoRepair 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 CIRCUITTurn 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.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?YesGo To 4NoRepair 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 CIRCUITTurn 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.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?YesGo To 5NoRepair 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 CIRCUITTurn 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.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?YesGo To 6NoRepair 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 CIRCUITTurn 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.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?YesGo To 7NoRepair 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 CIRCUITTurn 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.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?YesGo To 8NoRepair 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 SCOPEIgnition 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?YesReplace 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)NoGo To 9 9. PCMBefore 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?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)