P06A4 - Sensor Reference Voltage 4 Circuit Low

Theory of Operation

This sensor supply circuit provides a 5-Volt supply to the Accelerator Pedal Position 1 Sensor (APPS) and the A/C Pressure Sensor. The Powertrain Control Module (PCM) illuminates the MIL lamp immediately after the diagnostic runs and fails. The ETC lamp will also flash. During this time the customer will be in a limp home mode. The PCM will turn off the MIL lamp after the diagnostic runs and passes in four consecutive drive cycles.

When Monitored:

With the key on.

Set Condition:

Voltage detected on the 5-Volt supply circuit is below a calibrated value.

Possible Causes

5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
APP 1 SENSOR
A/C PRESSURE 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. ACTIVE DTC

1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.
Did the DTC reset?

Yes
• Go To 2

No

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

2. CHECK THE APP SENSOR 1

1. Ignition on.
2. Disconnect the Accelerator Pedal Position Sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Measure the voltage on the (F855) 5-Volt Supply circuit at the Accelerator Pedal Position Sensor harness connector.
Is the voltage reading between 4.9 and 5.1 Volts?

Yes
• Replace the Accelerator Pedal Position Sensor in accordance with the service information.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Go To 3

3. CHECK THE A/C PRESSURE SENSOR

1. Disconnect the A/C Pressure Sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
2. Measure the voltage on the (F855) 5-Volt Supply circuit at the A/C Pressure Sensor harness connector.
Is the voltage reading between 4.9 and 5.1 Volts?

Yes
• Replace the A/C Pressure Sensor in accordance with the service information.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Go To 4

4. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND

1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Check connectors - Clean/repair as necessary.
4. Measure the resistance between ground and the (F855) 5-Volt Supply circuit at the Accelerator Pedal
Position Sensor harness connector.
Is the resistance below 10k Ohms?

Yes
• Repair the (F855) 5-Volt Supply circuit for a short to ground.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Go To 5

5. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
1. Measure the resistance between the (F855) 5-Volt Supply circuit and all other circuits at the PCM C2 harness connector.
Is the resistance below 10k Ohms between the (F855) 5-Volt supply circuit and any of the circuits?

Yes
• Repair the short to the circuit that measured below 10k Ohms.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Replace and program the Powertrain Control Module in accordance with the Service Information.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).