P1618
P1618-SENSOR REFERENCE VOLTAGE 1 CIRCUIT ERRATIC
For a complete wiring diagram refer to: Electrical Diagrams
When Monitored
Ignition on
Set Condition
When the PCM recognizes the Primary 5-volt Supply circuit voltage is varying too much to quickly. One Trip Fault. ETC light is flashing.
Possible Causes
- (F855) PRIMARY 5-VOLT SUPPLY SHORTED TO GROUND
- (F855) PRIMARY 5-VOLT SUPPLY SHORTED TO BATTERY VOLTAGE
- (F855) PRIMARY 5-VOLT SUPPLY CIRCUIT OPEN 5-VOLT SENSOR
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running. With a scan tool, read DTCs.
Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. (F855) PRIMARY 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM harness connectors.
Disconnect all the Sensors that share the (F855) Primary 5-volt Supply circuit.
NOTE: This code can be caused by the improper installation of after market accessories that may be causing excessive noise on the (F855) 5-volt Supply circuit.
Measure the resistance between ground and the (F855) Primary 5-volt Supply circuit in the CKP Sensor harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short to ground in the (F855) Primary 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 3
3. SENSOR SHORTED TO GROUND
Connect the PCM harness connectors and all the previously disconnected Sensor except for the CKP Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the (F855) Primary 5-volt Supply circuit at the Throttle Body harness connector.
CAUTION: You must Turn the Ignition Off when disconnecting any of the Sensor harness connectors and Turn the Ignition On to check the voltage readings.
While monitoring the voltage, disconnect each Sensor harness connector that shares the (F855) Primary 5-volt Supply circuit, one at a time.
Does the voltage increase above 4.5 volts when disconnecting any of the Sensor harness connectors?
Yes >> Replace the Sensor that causes the (F855) Primary 5-volt Supply circuit voltage to increase when disconnected.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 4
4. 5-VOLT SENSOR
Turn the ignition off.
Connect all the previously disconnected Sensors except for the CKP Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the (F855) Primary 5-volt Supply circuit at the CKP Sensor harness connector.
Is the voltage between 4.8 and 5.2 volts?
Yes >> Replace the Crank Position Sensor.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 5
5. (F855) PRIMARY 5-VOLT SUPPLY SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the PCM harness connectors.
Disconnect all the Sensors that share the (F855) Primary 5-volt Supply circuit.
Ignition on, engine not running.
Measure the voltage on the (F855) Primary 5-volt Supply circuit in the CKP Sensor harness connector.
Is the voltage present?
Yes >> Repair the short to battery voltage in the (F855) Primary 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 6
6. (F855) PRIMARY 5-VOLT SUPPLY CIRCUIT OPEN
Turn the ignition off.
Reconnect all the sensors that were disconnected in the previous step except for the CKP Sensor harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance in the (F855) Primary 5-volt Supply circuit from the Sensor harness connector to the appropriate terminal of special tool #8815.
It may be necessary to perform this test from every sensor that uses the (F855) Primary 5-volt Supply circuit.
Is the resistance below 5.0 ohms?
Yes >> Go To 7
No >> Repair the open in the (F855) Primary 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test