For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0641: 5-Volt Reference 1 Circuit
DTC P0651: 5-Volt Reference 2 Circuit
DTC P0697: 5-Volt Reference 3 Circuit
DTC P06A3: 5-Volt Reference 4 Circuit

### Circuit/System Description

The engine control module (ECM) has 4 5-volt reference circuits. The ECM provides the 5-volt reference to various sensors. 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.

• | The ECM is not commanding reduced engine power.

• | The ignition voltage is greater than 6 volts.

• | The DTCs run continuously when the above conditions are met.

### Conditions for Setting the DTC

The ECM detects the 5-volt reference is out of range for less than 1 second.

### Action Taken When the DTC Sets

DTCs P0641, P0651, P0697, and P06A3 are Type A DTCs.

### Conditions for Clearing the DTC

DTCs P0641, P0651, P0697, and P06A3 are Type A DTCs.

### Diagnostic Aids

• | If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.

• | The scan tool 5-volt reference parameter should display between 4.8-5.2 volts.

#### P0641

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

• | The exhaust camshaft position (CMP) sensor

• | The intake camshaft position (CMP) sensor

• | The fuel tank pressure (FTP) sensor

• | The air conditioning (A/C) refrigerant pressure sensor

• | The vehicle speed (VSS) sensor

#### P0651

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

• | The clutch pedal position sensor

• | The crankshaft position (CKP) sensor

#### P0697

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

• | The accelerator pedal position (APP) sensor 2

• | The manifold absolute pressure (MAP) sensor

#### P06A3

The 5-volt reference 4 circuit provides 5 volts to the following sensors:

• | The accelerator pedal position (APP) sensor 1

• | The throttle position (TP) sensors 1

• | The throttle position (TP) sensor 2

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTCs P0641, P0651, P0697, and P06A3 should not set.
2. Engine idling, observe the following circuit status parameters:

• | 5 Volt Reference 1 Circuit Status

• | 5 Volt Reference 2 Circuit Status

• | 5 Volt Reference 3 Circuit Status

• | 5 Volt Reference 4 Circuit Status

• | Each parameter should display OK.

3. 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

Note: Additional DTCs will set when disconnecting components.

1. Ignition OFF, disconnect the harness connector at all appropriate sensors for the applicable DTC. Refer to Diagnostic Aids.
2. Ignition ON, test for 4.8-5.2 V between one of the 5-volt reference circuits and ground.

⇒ | If less than the specified range, test for a short to ground on the 5-volt reference circuit. If all circuits test normal, replace the control module.

⇒ | If greater than the specified range, test for a short to voltage on the 5-volt reference circuit. If all circuits test normal, replace the control module.

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

3. Connect each component associated with the 5-volt reference circuit one at a time while monitoring the scan tool 5 volt reference parameter. The voltage should display 5.0 V.

⇒ | If not the specified value, test the signal circuit of the 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.

• | Accelerator Pedal Position Sensor Replacement

• | Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement

• | Manifold Absolute Pressure Sensor Replacement

• | Throttle Body Assembly Replacement

• | Crankshaft Position Sensor Replacement

• | Camshaft Position Sensor Replacement

• | Vehicle Speed Sensor Inspection

• | Fuel Tank Pressure Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming