For a complete wiring diagram Refer to Section 8W.When Monitored:With the ignition on and no other APPS No.2 DTCs present.Set Condition:When the APP Sensor No.2 voltage is too low. Engine will only idle if the Brake pedal is Pressed or has 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(F856) 5-VOLT SUPPLY CIRCUIT OPEN(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND(K29) APP SIGNAL 2 CIRCUIT OPEN(K29) APP SIGNAL 2 CIRCUIT SHORTED TO GROUND(K29) APP SIGNAL 2 CIRCUIT SHORTED TO THE (K167) APP RETURN 1 CIRCUIT(K29) APP SIGNAL 2 CIRCUIT SHORTED TO THE (K400) APP RETURN 2 CIRCUITAPP SENSORPCMAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).1. APP SENSOR BELOW 0.25 OF A VOLTWhen 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, read the APP Sensor No.1 voltage.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 0.25 of a volt?YesGo To 2NoGo To 112. (F856) 5-VOLT SUPPLY CIRCUIT

Turn the ignition off.Disconnect the APP Sensor harness connector.Ignition on, engine not running.Measure the voltage on the (F856) 5-volt Supply circuit in the APP Sensor harness connector.Is the voltage between 4.5 and 5.2 volts?YesGo To 3NoGo To 83. ACCELERATOR PEDAL POSITION SENSOR

Connect a jumper wire between the (F856) 5-volt Supply circuit and the (K29) APP Signal circuit 2 in the Sensor harness connector.With a scan tool, monitor the APP Sensor No.2 voltage.Is the voltage above 4.5 volts with the jumper wire installed?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 4Remove the jumper wire before continuing.4. (K29) APP SIGNAL 2 CIRCUIT OPEN

Turn the ignition off.Disconnect the C3 PCM 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 to perform diagnosis.Measure the resistance of the (K29) APP Signal 2 circuit from the APP Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 5NoRepair the open in the (K29) APP Signal 2 circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)5. (K29) APP SIGNAL 2 CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (K29) APP Signal 2 circuit in the APP Sensor harness connector.Is the resistance below 100 ohms?YesRepair the short to ground in the (K29) APP Signal 2 circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 66. (K29) APP SIGNAL 2 CIRCUIT SHORTED TO THE (K400) APP RETURN 2 CIRCUIT

Measure the resistance between the (K29) APP Signal 2 circuit and the (K400) APP Return 2 circuit in the APP Sensor harness connector.Is the resistance below 100 ohms?YesRepair the short between the (K400) APP Return 2 circuit and the (K29) APP Signal 2 circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 77. (K29) APP SENSOR NO.2 SIGNAL CIRCUIT SHORTED TO THE (K167) APP SENSOR NO.1 RETURN CIRCUIT

Measure the resistance between the (K29) APP Signal 2 circuit and the (K167) APP Return 2 circuit in the APP Sensor harness connector.Is the resistance below 100 ohms?YesRepair the short between the (K167) APP Return 1 circuit and the (K29) APP Signal 2 circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 108. (F856) 5-VOLT SUPPLY CIRCUIT OPEN

Turn the ignition off.Disconnect the C1 PCM 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 to perform diagnosis.Measure the resistance of the (F856) 5-volt Supply circuit from the Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 9NoRepair the open in the (F856) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)9. (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (F856) 5-volt Supply circuit in the APP Sensor harness connector.Is the resistance below 100 ohms?YesRepair the short to ground in the (F856) 5-volt Supply circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 1010. 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)11. APP SENSOR SWEEP Ignition on, engine not running.With a scan tool, monitor the APP Sensor No.2 voltage.Slowly press the Accelerator pedal down.Does voltage start at approximately 0.22 of a volt and go above 2.31 volts with a smooth transition?YesRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace 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)