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DTC P0642, P0643, P0652, or P0653

The engine control module (ECM) has 2 internal 5 V reference circuits called 5 V reference 1 and 5 V reference 2. Each reference circuit provides 5 V reference circuits for more than one sensor. A fault condition on one 5 V reference circuit will affect the other 5 V reference circuits connected to that reference circuit. The ECM monitors the voltage on the 5 V reference circuits.

The 5 V reference 1 circuit provides 5 V to the following sensors:

The 5 V reference 2 provides 5 V to the following sensors:

The crankshaft position sensor

The ECM detects a voltage out of range condition on the 5 V reference 1 or 2 circuit for more than 0.5 s.

DTCs P0642 00, P0643 00, P0652 00, and P0653 00 are Type A DTCs.

DTCs P0642 00, P0643 00, P0652 00, and P0653 00 are Type A DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

1. Ignition ON, observe the DTC information with a scan tool. DTCs P0642 00, P0643 00, P0652 00, and P0653 00 should not set on this ignition cycle.
2. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

1. Ignition OFF, disconnect the harness connector for the appropriate sensor 5 V reference circuit DTC being diagnosed:

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

•	5 V reference 1: B74 Manifold Absolute Pressure Sensor

•	5 V reference 1: B25B Clutch Pedal Position Sensor

•	5 V reference 1: B1 A/C Refrigerant Pressure Sensor

•	5 V reference 1: B150 Fuel Tank Pressure Sensor

•	5 V reference 2: B26 Crankshaft Position Sensor

2. Ignition ON, test for 4.8-5.2 V between each of the 5 V reference circuits and ground at the following component terminals:

•	B74 Manifold Absolute Pressure Sensor circuit terminal C (X1)

•	B25B Clutch Pedal Position Sensor circuit terminal C (X1)

•	B1 A/C Refrigerant Pressure Sensor circuit terminal 2 (X1)

•	B150 Fuel Tank Pressure Sensor circuit terminal 3 (X1)

•	B26 Crankshaft Position Sensor circuit terminal 3 (X1)

⇒	If the voltage is less than the specified value, test for a short to ground on all the 5 V reference circuits. If all circuits test normal, replace the K20 Engine Control Module.

⇒	If the voltage is greater than the specified value, test for a short to voltage on all the 5 V reference circuits. If all circuits test normal, replace the K20 Engine Control Module.

3. Connect each component associated with the 5 V reference circuit, one at a time, while monitoring the voltage. Verify the voltage remains between 4.8-5.2 V.

⇒	If the voltage display is not within the specified range when a component is connected, test the signal circuit for a short to voltage. If all circuits test normal, replace the appropriate component.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.