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 CircuitDTC P0651: 5-Volt Reference 2 Circuit
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|
Accelerator Pedal Position (APP) Sensor 2 5-Volt Reference 1 Circuit | P0641, P2228, P0532, P0452, P0107 | P2127 | P0533, P0641, P2229, P2261 |
Accelerator Pedal Position (APP) Sensor 1 5-Volt Reference 2 Circuit | P0651 | P2122 | P0651 |
Air Conditioning (A/C) Refrigerant Pressure Sensor 5-Volt Reference 1 Circuit | P0641, P0107, P0 452, P0532, P2228, P0069, P0522, P0 390, P0365, P0345, P0340¹ | ||
Fuel Tank Pressure (FTP) Sensor 5-Volt Reference 1 Circuit | P0641 P0107, P0452, P0532, P2228, P0069, P0522, P0390, P0365, P0345, P0340 | ||
Manifold Absolute Pressure (MAP) Sensor 5-Volt Reference 2 Circuit | P0651, P2228, P0532, P0452, P0107, P0522 | ||
Throttle Position (TP) Sensor 1 and 2 5-Volt Reference 1 Circuit | P0641 | ||
Engine Oil Pressure (EOP) Sensor 5-Volt Reference 1 Circuit | P0641, P0107, P0 452, P0532, P2228, P0069, P0522, P0 390, P0365, P0345, P0340¹ | ||
Crankshaft Position (CKP) Sensor 5-Volt Reference 2 Circuit | P0651 | ||
Camshaft Position (CMP) Sensor Bank 1 Exhaust 5-Volt Reference 1 Circuit | P0641 P0107, P0452, P0532, P2228, P0069, P0522, P0390, P0365, P0345, P0340 | ||
Camshaft Position (CMP) Sensor Bank 1 Intake 5-Volt Reference 1 Circuit | P0641 P0107, P0452, P0532, P2228, P0069, P0522, P0390, P0365, P0345, P0340 | ||
Camshaft Position (CMP) Sensor Bank 2 Exhaust 5-Volt Reference 1 Circuit | P0641 P0107, P0452, P0532, P2228, P0069, P0522, P0390, P0365, P0345, P0340 | ||
Camshaft Position (CMP) Sensor Bank 2 Intake 5-Volt Reference 1 Circuit | P0641 P0107, P0452, P0532, P2228, P0069, P0522, P0390, P0365, P0345, P0340 | ||
¹Engine cranks but does not start | |||
Circuit/System Description
The control module has 2 internal 5-volt reference busses called 5-volt reference 1 and 5-volt reference 2. Each reference bus provides a 5-volt reference for more than one sensor. Therefore, a fault condition at one 5-volt reference circuit will affect the other 5-volt reference circuits connected to that reference bus. The control module monitors the voltage on the 5-volt reference bus.
The 5-volt reference 1 bus provides 5 volts to the following sensors:
| • | The air conditioning (A/C) refrigerant pressure sensor |
| • | The throttle position (TP) sensor 1 and 2 |
| • | The fuel tank pressure (FTP) sensor |
| • | The accelerator pedal position (APP) sensor 2 |
| • | Camshaft Position (CMP) Sensor |
| • | The Engine Oil Pressure (EOP) sensor |
The 5-volt reference 2 bus provides 5 volts to the following sensors:
| • | The APP sensor 1 |
| • | Crankshaft Position (CKP) Sensor |
| • | The Manifold Absolute Pressure (MAP) Sensor |
Conditions for Running the DTC
| • | DTC P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P1680, P2610 are not set. |
| • | The ignition switch is in Unlock, Accessory, Run or Crank. |
| • | The ignition voltage is greater than 5.23 volts. |
| • | DTCs P0641 and P0651 run continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The control module detects a voltage out of tolerance condition on the 5-volt reference 1 or 2 bus. |
| • | It occurs 39 times during the 19 tests. |
Action Taken When the DTC Sets
DTCs P0641 and P0651 are Type A DTCs.
Conditions for Clearing the DTC
DTCs P0641 and P0651 are Type A DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
P0641
With the engine OFF, turn the ignition ON, observe the MAP sensor voltage parameter with a scan tool. When the system is operating correctly, the scan tool should display approximately 2.2 volts.
P0651
With the engine OFF, turn the ignition ON, observe the APP sensor 1 voltage parameter with a scan tool. When the system is operating correctly, the scan tool should display approximately 0.96 volt.
Circuit/System Testing
P0641
- Disconnect the throttle body electrical connector.
- With the engine OFF, turn the ignition ON, measure the MAP sensor for 4.8-5.2 volts between the 5-volt reference circuit terminal E and ground.
- Continue to measure the voltage between the throttle 5-volt reference circuit terminal E and ground. Monitor the DMM while disconnecting all other sensors connected to the 5-volt reference 1 bus.
- Reconnect all sensors.
- Measure for 4.8-5.2 volts from the 5 volt reference circuit terminal B of the A/C refrigerant pressure sensor to ground.
- If all circuits test normal, replace the ECM.
| ⇒ | If the voltage is more than 5.2 volts, test for a short to voltage on the 5-volt reference circuits of all the sensors connected to the 5-volt reference 1 bus, test for a short to voltage on the FTP sensor signal circuit. |
| ⇒ | If the voltage is less than 4.8 volts, test for a short to ground on the 5-volt reference circuits of all the sensors connected to the 5-volt reference 1 bus. |
| ⇒ | If the voltage returns to 4.8-5.2 volts when a sensor is disconnected, replace the applicable sensor. |
| ⇒ | If the voltage is not within 4.8-5.2 volts, test the throttle body signal circuit for a short to voltage or the throttle body is inoperative. |
P0651
- Disconnect the MAP sensor electrical connector.
- With the engine OFF, turn the ignition ON, measure for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.
- Continue to measure the MAP sensor electrical connector between the 5-volt reference circuit terminal C and ground. Monitor the DMM while disconnecting APP sensor 1.
- If all circuits test normal, replace the ECM.
| ⇒ | If the voltage is more than 5.2 volts, test for a short to voltage on the 5-volt reference circuits of the 5-volt reference 2 bus. |
| ⇒ | If the voltage is less than 4.8 volts, test for a short to ground on the 5-volt reference circuits of the 5-volt reference 2 bus. |
| ⇒ | If the voltage returns to 4.8-5.2 volts when APP sensor 1 is disconnected, replace the APP sensor. |
| ⇒ | If the voltage returns to 4.8-5.2 volts when APP sensor 1 is disconnected, replace the MAP sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Accelerator Pedal Position Sensor Replacement Accelerator Pedal Position Sensor Replacement |
| • | Control Module References for ECM replacement, setup, and programming |
