P1618-SENSOR REFERENCE VOLTAGE 1 ERRATIC

For a complete wiring diagram, refer to the Wiring Information.

When Monitored:
With the ignition on.
Set Condition:
The Powertrain Control Module (PCM) detects an excessive voltage variation on the 5-Volt supply circuit.

Possible Causes
5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE
ACCELERATOR PEDAL POSITION SENSOR
CAMSHAFT 2 POSITION SENSOR
THROTTLE POSITION SENSOR
CRANKSHAFT POSITION SENSOR
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

1. DTC IS ACTIVE

1.	Start the engine and allow it to reach normal operating temperature.

WARNING:

When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2.	With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go To 2

Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

2. (F855) 5-VOLT SUPPLY CIRCUIT VOLTAGE

1.	Turn the ignition off.

2.	Disconnect the Throttle Body harness connector.

3.	Turn the ignition on.

4.	Measure the voltage of the (F855) 5-Volt Supply circuit.

Select the appropriate response from the list below:

Voltage more than 5.2 Volts

Repair the (F855) 5 Volt Supply circuit for a short to voltage.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Voltage between 4.8 and 5.2 Volts

Go To 3

3. THROTTLE BODY

1.	Turn the ignition off.

2.	Connect the Throttle Body harness connector.

3.	Disconnect the oil pressure sensor harness connector.

4.	Turn the ignition on.

5.	Measure the voltage of the (F855) 5 Volt Supply circuit at the oil pressure sensor harness connector.

Is the voltage between 4.7 and 5.2 Volts?

Yes

Replace the Throttle Body in accordance with the service information because the Throttle Body is pulling the 5 volt supply low.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To\ 4

4. OIL PRESSURE SENSOR

1.	Turn the ignition off.

2.	Disconnect the oil pressure sensor harness connector.

3.	Turn the ignition on.

4.	Continue measuring the voltage of the (F855) 5 Volt Supply circuit at the Throttle Body harness connector.

Is the voltage between 4.7 and 5.2 Volts?

Yes

Replace the oil pressure sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 5

5. CRANKSHAFT POSITION SENSOR

1.	Turn the ignition off.

2.	Disconnect the Crankshaft Position Sensor harness connector.

3.	Turn the ignition on.

4.	Continue measuring the voltage of the (F855) 5 Volt Supply circuit at the Throttle Body harness connector.

Is the voltage between 4.7 and 5.2 Volts?

Yes

Replace the Crankshaft Position Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 6

6. 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

1.	Turn the ignition off.

2.	Disconnect the PCM harness connectors.

3.	Measure the resistance between ground and the (F855) 5-Volt Supply circuit.

Is the resistance above 1000 Ohms?

Yes

Go To 7

Repair the 5-Volt Supply circuit for a short to ground.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

7. 5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE

1.	Turn the ignition off.

2.	Measure the resistance of the (F855) 5-Volt Supply circuit between the Oil Pressure Sensor harness connector and the PCM harness connector.

3.	Measure the resistance of the (F855) 5-Volt Supply circuit between the Crankshaft Position Sensor harness connector and the PCM harness connector.

4.	Measure the resistance of the (F855) 5-Volt Supply circuit between the Throttle Body harness connector and the PCM harness connector.

Is the resistance below 5.0 Ohms for all of the circuits?

Yes

Go To 8

Repair the 5-Volt Supply circuit for an open circuit or high resistance.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

8. POWERTRAIN CONTROL MODULE (PCM)

1.	Inspect the (F855) 5-Volt Supply circuit between the Oil pressure sensor harness connector and the PCM harness connector.

2.	Inspect the (F855) 5-Volt Supply circuit between the Crankshaft Position Sensor harness connector and the PCM harness connector.

3.	Inspect the (F855) 5-Volt Supply circuit between the Throttle Body harness connector and the PCM harness connector.

4.	Inspect all PCM power and ground circuits.

5.	Look for any chafed, pierced, pinched, or partially broken wires.

6.	Look for broken, bent, pushed out or corroded terminals.

7.	Perform any Technical Service Bulletins that may oil pressure.

Were any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control - Removal) .
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

P1618-SENSOR REFERENCE VOLTAGE 1 ERRATIC

Possible Causes