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P0091




DTC P0090-P0092, P00C8, P00C9, or P00CA

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P0090
- Fuel Pressure Regulator Control Circuit

DTC P0091
- Fuel Pressure Regulator Control Circuit Low Voltage

DTC P0092
- Fuel Pressure Regulator Control Circuit High Voltage

DTC P00C8
- Fuel Pressure Regulator High Control Circuit

DTC P00C9
- Fuel Pressure Regulator High Control Circuit Low Voltage

DTC P00CA
- Fuel Pressure Regulator High Control Circuit High Voltage

Diagnostic Fault Information





Circuit/System Description

High pressure fuel is regulated by the high pressure fuel pump actuator, which is a part of the high pressure fuel pump. The high pressure fuel pump actuator is a solenoid valve. The ECM provides battery voltage on the actuator high control circuit and ground on the actuator low control circuit. Both circuits are controlled through output drivers within the ECM. When deactivated, both drivers are disabled. When activated, the high control circuit driver energizes the high pressure fuel pump actuator and the low control circuit driver pulse-width modulates (PWM) the low control circuit to ground. The ECM monitors the voltage on the circuits to detect a failure.

Conditions for Running the DTC

* The ignition voltage is greater than 11 V.
* The engine speed is greater than 50 RPM.
* The DTCs run continuously within the enabling conditions.

Conditions for Setting the DTC

P0090
* The ECM detects an open circuit in the high pressure fuel pump actuator low control circuit.
* The DTC sets when the above condition is present for 4 s.

P0091
* The ECM detects a short to ground in the high pressure fuel pump actuator low control circuit.
* The DTC sets when the above condition is present for 4 s.

P0092
* The ECM detects a short to voltage in the high pressure fuel pump actuator low control circuit.
* The DTC sets when the above condition is present for 4 s.

P00C8
* The ECM detects an open circuit in the high pressure fuel pump actuator high control circuit.
* The DTC sets when the above condition is present for 4 s.

P00C9
* The ECM detects a short to ground in the high pressure fuel pump actuator high control circuit.
* The DTC sets when the above condition is present for 4 s.

P00CA
* The ECM detects a short to voltage in the high pressure fuel pump actuator high control circuit.
* The DTC sets when the above condition is present for 4 s.

Action Taken When the DTC Sets

* DTCs P0090, P0091, P0092, P00C8, P00C9, and P00CA are Type A DTCs.
* A message center or an indicator displays Reduced Engine Power.

Conditions for Clearing the DTC

DTCs P0090, P0091, P0092, P00C8, P00C9, and P00CA are Type A DTCs.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Fuel System Description (Fuel System Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Observe the DTC information with a scan tool. DTC P0090, P0091, P0092, P00C8, P00C9, P00CA, P0685, or P1682 should not set.

• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.

2. Ignition ON, command the Fuel Pressure Regulator ON and OFF with a scan tool while observing the following control circuit status parameters:

* Fuel Pressure Regulator Control Circuit High Voltage Test Status
* Fuel Pressure Regulator Control Circuit Open Test Status
* Fuel Pressure Regulator Control Circuit Low Voltage Test Status
* Fuel Pressure Regulator High Control Circuit High Voltage Test Status
* Fuel Pressure Regulator High Control Circuit Open Test Status
* Fuel Pressure Regulator High Control Circuit Low Voltage Test Status
Each parameter should toggle between OK and Not Run or Not Run and OK.

3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
2. Ignition ON, verify that a test lamp does not illuminate between the high control circuit terminal 2 and ground and the low control circuit terminal 1 and ground.

• If the test lamp illuminates, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

3. Verify that a test lamp does not illuminate between the high control circuit terminal 2 and B+ and the low control circuit terminal 1 and B+.

• If the test lamp illuminates, test the appropriate control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

4. Connect a 3 A fused jumper wire between the high control circuit terminal 2 and ground. The Fuel Pressure Regulator High Control Circuit Open Test Status should transition from Malfunction to OK and the Fuel Pressure Regulator High Control Circuit Low Voltage Test Status should transition from OK to Malfunction.

• If not the specified value, test the high control circuit for an open/high resistance.

5. Connect a 3 A fused jumper wire between the low control circuit terminal 1 and B+. The Fuel Pressure Regulator Control Circuit Open Test Status should transition from Malfunction to OK and the Fuel Pressure Regulator Control Circuit High Voltage Test Status should transition from OK to Malfunction.

• If not the specified value, test the low control circuit for an open/high resistance.

6. If all circuits test normal, test or replace the G18 high pressure fuel pump.

Component Testing

Static Test
1. Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.

Note: The DMM and test leads must be calibrated to 0 ohm in order to prevent misdiagnosis.

2. Test for 9-11 ohm at 25°C (77°F) between the low control circuit terminal 1 and the high control circuit terminal 2 at the G18 high pressure fuel pump.

• If not within the specified range, replace the G18 high pressure fuel pump.

3. Measure the resistance between each terminal and the high pressure fuel pump housing. The DMM should display OL.

• If less than the specified value, replace the G18 high pressure fuel pump.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Fuel Pump Replacement (Fuel Pump Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming

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