P129F

P129F- FUEL PUMP - HIGH SPEED MODE PERFORMANCE - HEV





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

Theory of Operation

The purpose of the Dual Speed Fuel Pump (DSFP) feature is to reduce electrical demand by lowering the current draw of the fuel pump when the fuel flow rate is low. The DSFP uses the normal fuel pump relay circuitry with an additional relay to switch a resistor (voltage divider) into the circuit. Switching the resistor (low speed) into the circuit will reduce the fuel pump voltage from roughly 14v to 10v. The diagnostic uses a feedback from the input voltage to the pump. The desired state is then compared against the actual state to evaluate whether or not the circuitry is performing appropriately.

- When Monitored:
Vehicle is in ready mode, battery voltage 10.4

- Set Condition:
This PCM compares the circuit feedback to a calibrated range (Greater than 0.935 Less than 0.7) when the circuit is energized.





WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury

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

1. DTC IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, Clear DTCs in the Powertrain Control Module (PCM).
3. With the scan tool, actuate the SRV Solenoid Control State.
4. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic Procedure. Intermittent Condition Test

2. (N1) FUEL PUMP RELAY OUTPUT CIRCUIT OPEN OR HIGH RESISTANCE
1. Disconnect the C3 PCM 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 the PCM Pinout Box 8815 to perform diagnosis.

2. Measure the resistance of the (N1) fuel pump relay output circuit from the relay connection to the appropriate terminals of the PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms?

Yes

- Go To 3

No

- Repair the (N1) fuel pump relay output circuit for an open circuit or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. (K317) DSFP VOLTAGE REDUCER CIRCUIT SHORTED TO GROUND
1. Turn the ignition on
2. Measure the resistance of the (K317) DSFP voltage reducer circuit at the Relay connection to ground.

Is the voltage above 1.0 volt?

Yes

- Repair the short to ground on the (K317) DSFP voltage reducer circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Short Runner Valve Assembly and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Search for any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.