P1618-SENSOR REFERENCE VOLTAGE 1 CIRCUIT ERRATIC

For a complete wiring diagram Refer to Section 8W.

When Monitored:
Ignition on.
Set Condition:
When the PCM recognizes the Primary 5-volt Supply circuit voltage is varying too much too 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. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1.ACTIVE DTC

Is the DTC Active at this time?

Yes

Go To 2

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

2.(F855) PRIMARY 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

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.

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (F855) Primary 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 3

3.SENSOR SHORTED TO GROUND

NOTE: You must Turn the Ignition Off when disconnecting any of the Sensor harness connectors and Turn the Ignition On to check the voltage readings.

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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 4

4.5-VOLT SENSOR

Is the voltage between 4.8 and 5.2 volts?

Yes

Replace the Crank Position Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 5

5.(F855) PRIMARY 5-VOLT SUPPLY SHORTED TO BATTERY VOLTAGE

Is the voltage above 0 volts?

Yes

Repair the short to battery voltage in the (F855) Primary 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 6

6.(F855) PRIMARY 5-VOLT SUPPLY CIRCUIT OPEN

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.

Is the resistance below 5.0 ohms?

Yes

Go To 7

Repair the open in the (F855) Primary 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Were there any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)