P0643-SENSOR REFERENCE VOLTAGE 1 CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W
Possible Causes
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INTERMITTENT DTC
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(K356) BOOST PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
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(K350) FUEL PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
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(K844) CAMSHAFT POSITION SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
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ENGINE CONTROL MODULE
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Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Theory of Operation
The ECM contains 3 internal 5–Volt Sensor Supply sources. Each 5–Volt Supply source is split into parallel circuits to provide 5 volts to multiple sensors. Sensor Supply 1 provides
5 volts to the Camshaft Position Sensor, Boost Pressure Sensor and the Fuel Pressure Sensor.
Diagnostic Test
1.
CHECK FOR ACTIVE DTC
Turn the ignition on.
With the scan tool, erase ECM DTCs.
Turn the ignition off for 10 seconds.
Turn the ignition on.
With the scan tool, View DTCs.
Is the status Active for this DTC?
Yes
No
2.
(K356) BOOST PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the Boost Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ASD Relay from the TIPM.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage on the (K356) Boost Pressure Sensor 5 Volt Supply circuit at the Boost Pressure Sensor harness connector.
Is the voltage below 1.0 volt?
Yes
No
3.
(K844) CAMSHAFT POSITION SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the Camshaft Position Sensor harness connector.
NOTE:
The jumper wire should still be in place.
Turn the ignition on.
Measure the voltage on the (K844) Camshaft Position Sensor 5 Volt Supply circuit at the CMP Sensor harness connector.
Is the voltage below 1.0 volt?
Yes
No
4.
(K350) FUEL PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the Fuel Pressure Sensor harness connector.
NOTE:
The jumper wire should still be in place.
Turn the ignition on.
Measure the voltage on the (K350) Fuel Pressure Sensor 5 Volt Supply circuit at the Fuel Pressure Sensor harness connector.
Is the voltage below 1.0 volt?
Yes
No
5.
ENGINE CONTROL MODULE (ECM)
Turn the ignition off.
Remove the jumper wire and install the ASD relay.
Inspect the (K356) Boost Pressure Sensor 5 Volt Supply circuit between the Boost Pressure Sensor harness connector and the ECM harness connector.
Inspect the (K844) Camshaft Position Sensor 5 Volt Supply circuit between the CMP harness connector and the ECM harness connector.
Inspect the (K350) Fuel Pressure Sensor 5 Volt Supply circuit between the Fuel Pressure Sensor harness connector and the ECM harness connector
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Refer to any Technical Service Bulletins that may apply.
Were any problems found?
Yes
No