P018B

P018B-FUEL PRESSURE SENSOR CIRCUIT PERFORMANCE

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

Theory of Operation

The Powertrain Control Module (PCM) provides a 5-Volt supply to the Fuel Rail Pressure Sensor (FRPS). The PCM also provides a ground on the sensor return circuit. The Fuel Rail Pressure Sensor provides a signal to the PCM on the Fuel Rail Pressure Sensor Signal circuit. This sensor signal voltage changes based on the pressure in the fuel rail. The PCM will detect a low signal voltage at low rail pressures. The PCM will detect a high signal voltage during high rail pressure conditions. The PCM will light the MIL lamp immediately after the diagnostic runs and fails. During this time the customer may experience a power and or speed derate. The PCM will turn off the MIL light after the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
With the ignition on and battery voltage greater than 10.4 Volts.

- Set Conditions:
At idle, the rate of change in fueling with respect to the rate of change of pressure is below the calibrated fail high threshold or above the calibrated fail low threshold while the monitor was running.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. ACTIVE DTC

NOTE: If a 5-Volt reference DTC is present, repair that DTC before proceeding with this test.

NOTE: If DTC P018C or P018D are present, repair that DTC before proceeding with this test.

1. Turn the ignition on.
2. With the scan tool, read DTCs.

Is the DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE (K181) FRPS SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the FRPS harness connector and the PCM C1 harness connector.
3. Measure the resistance of the (K181) FRPS Signal circuit between the FRPS harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 3

No

- Repair the (K181) FRPS Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. CHECK THE (K914) SENSOR GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K914) FRPS Ground circuit between the FRPS harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Replace the Fuel Rail Pressure Sensor.
- Go To 4

No

- Repair the (K914) Sensor Ground circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. POWERTRAIN CONTROL MODULE
1. Let the engine run until it reaches normal operating temperature.
2. Using the scan tool, record any DTCs.

Did the DTC return?

Yes

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Repair is complete.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.