P0642

DTC P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698 or P0699

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0642
- 5 Volt Reference 1 Circuit Low Voltage

DTC P0643
- 5 Volt Reference 1 Circuit High Voltage

DTC P0652
- 5 Volt Reference 2 Circuit Low Voltage

DTC P0653
- 5 Volt Reference 2 Circuit High Voltage

DTC P0698
- 5 Volt Reference 3 Circuit Low Voltage

DTC P0699
- 5 Volt Reference 3 Circuit High Voltage

Circuit/System Description

The engine control module (ECM) has 3 5-volt reference circuits. The ECM provides the 5-volt reference to various sensors. Each reference circuit provides a 5-volt reference for greater than one sensor. A short to ground or voltage on one of the 5-volt reference circuits will affect all components connected to that 5-volt reference circuit. The ECM monitors the voltage on the 5-volt reference circuits.

Conditions for Running the DTC

* The ignition is ON for greater than 3 seconds.
* DTCs P0642, P0643, P0652, P0653, P0698, and P0699 run continuously when the above condition is met.

Conditions for Setting the DTC

The 5-volt reference circuit voltage is above or below a predetermined threshold for greater than 1 second or for a cumulative time of 10 seconds.

Action Taken When the DTC Sets

DTCs P0642, P0643, P0652, P0653, P0698, and P0699 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0642, P0643, P0652, P0653, P0698, and P0699 are Type A DTCs.

Diagnostic Aids

* The 5-volt reference 1 circuit provides 5 volts to the following sensors:

- The fuel tank pressure (FTP) sensor
- The engine oil pressure (EOP) sensor

* The 5-volt reference 2 circuit provides 5 volts to the following sensors:

- All four camshaft position (CMP) sensors
- Accelerator pedal position (APP) sensor 1

* The 5-volt reference 3 circuit provides 5 volts to the following sensors:

- Throttle position sensor (TPS) 1 and 2
- Crankshaft position (CKP) sensor
- Accelerator pedal position (APP) sensor 2
- A/C pressure sensor

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTC P0642, P0643, P0652, P0653, P0698, or P0699 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Important: Additional DTCs will set when disconnecting the components.

1. Ignition OFF, disconnect the harness connector of all appropriate sensors for the applicable DTC.
2. Ignition ON, measure for 4.6-5.2 volts between one of the 5-volt reference circuits and ground.

^ If the voltage is less than the specified range, test for a short to ground on all the 5-volt reference circuits. If all circuits test normal, replace the control module.
^ If the voltage is greater than the specified range, test for a short to voltage on all the 5-volt reference circuits for each component associated with the appropriate 5-volt reference circuit. If all circuits test normal, replace the control module.

Important: A short to voltage on the signal circuit of certain components may cause this DTC to set.

3. Connect each component associated with the affected 5-volt reference circuit one at a time, while monitoring the appropriate 5-Volt Reference Circuit Status parameter with a scan tool. The parameter should continue to display OK.

^ If the parameter displays Fault when a component is connected, test the signal circuit of that component for a short to voltage. If the circuit tests normal, replace the component.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Accelerator Pedal Position Sensor Replacement
* Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement (LNJ) Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement (LY7)
* Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust
* Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake
* Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust
* Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake
* Crankshaft Position Sensor Replacement
* Engine Oil Pressure Sensor and/or Switch Replacement
* Fuel Tank Pressure Sensor Replacement
* Throttle Body Assembly Replacement.