Pinpoint Test C: Low Pressure Fuel Pump Tests
- C1: CHECK LOW PRESSURE FUEL PUMP ACTIVITY
- Remove the lower rear seat cushion. Refer to the appropriate repair information.
- Use an assistant to cycle the ignition status between On and Off to operate the low pressure pump. Make sure the engine remains off
- Listen for a humming sound from the fuel pump for a couple of seconds
Can the fuel pump be heard running?
Yes: GO to C4.
No: GO to C2.
- C2: CHECKING LOW PRESSURE FUEL PUMP FUSE
- Locate the fuel pump fuse in the Rear Junction Box (RJB)
- Check the fuel pump fuse
has the fuel pump fuse blown?
Yes: Refer to the electric circuit diagrams and check the fuel pump circuit for short circuit to power or short circuit to ground. Repair circuit as necessary. Install a new fuse and retest
No: GO to C3.
- C3: CHECKING LOW PRESSURE FUEL PUMP RELAY
- Using the manufacturer approved diagnostic system, find the datalogger signal for the fuel pump relay control button. Use this button to switch the fuel pump relay ON and OFF
Can the fuel pump relay be heard clicking each time it is turned ON and OFF
Yes: GO to C4.
No: Check the ampere rate of the relay. Check the fuel pump relay circuit for short circuit to ground. Repair as necessary and retest if the relay is not functioning, if the ampere rate of the relay is different replace it with a 70A relay
- Using the manufacturer approved diagnostic system, find the datalogger signal for the fuel pump relay control button. Use this button to switch the fuel pump relay ON and OFF
- C4: LOW PRESSURE FUEL PUMP VOLTAGE DROP TEST NOTE: This test should be completed by turning the ignition ON.
- Connect the manufacturers approved battery support unit
- Go back to the fuel pump
- Use the manufacturer approved oscilloscope
- Connect the oscilloscope to the low pressure fuel pump connector (C4MC11B)
- Turn the ignition ON and record the outcome
Are the voltage values constantly oscillating between 0V and 13.5V in each of the phases as shown in the above figures?
Yes: GO to PINPOINT TEST D .
No: GO to C5.
- C5: LOW PRESSURE FUEL PUMP RESISTANCE TEST 1
- Disconnect the electrical connector on top of the fuel pump flange
- Use the manufacturer approved oscilloscope
- Check the resistance between terminal 1 and 2, 1 and 3, 2 and 3 of the low pressure fuel pump using an ohmmeter
- Check if there is any evidence of frayed, melted wires/connectors or corroded connector pins
Is there any open or short circuit in the fuel pump connector or internal circuit? (Expected resistance value in the specified terminals is 0.5Ω)
Yes: Low pressure fuel pump internal failure. Install a new low pressure fuel pump.
No: GO to C6.
- C6: LOW PRESSURE FUEL PUMP RESISTANCE TEST 2
- Reconnect the electrical connector on top of the fuel pump module flange
- Locate the Fuel Pump Driver Module (FPDM)
- Disconnect the electrical connector of the FPDM
- Use the manufacturer approved ohmmeter
- Check the resistance between terminal 1 and 2, 1 and 5, 2 and 5 of the FPDM
harness side connector using an ohmmeter
Is there any open or short circuit in the wiring harness between FPDM and Low pressure fuel pump? (Expected resistance value in the specified terminals is 1Ω)
Yes: Repair the suspected wiring harness as required. (Refer to the appropriate system wiring diagrams)
No: GO to C7.
- C7: LOW PRESSURE FUEL PUMP GROUND CIRCUIT CHECK
- Get a long wire lead that can reach the fuel pump and attach it to the -VE terminal of the battery
- Use the manufacturers approved multimeter
- Attach the -VE lead of the multimeter to the long wire lead which is attached to the battery -VE terminal
- Attach the +VE lead of the multimeter to the -VE terminal of the FPDM (Terminal 8)
- Set the multimeter to Vehicle Domain Controller (VDC)
- Turn the ignition ON
- Measure the voltage
Is the voltage drop >1V?
Yes: Check the ground connection of the FPDM and Repair as required. (Refer to the appropriate system wiring diagrams)
No: GO to C8.
- C8: LOW PRESSURE FUEL PUMP VOLTAGE DROP TEST IN THE +VE CIRCUIT
- Get a long wire lead that can reach the FPDM and attach it to the +VE terminal of the battery
- Attach the +VE lead of the multimeter to the long wire lead which is attached to the battery
- Attach the -VE terminal of the multimeter to the +VE terminal of the FPDM (Connector harness side: C1E528 terminal 4)
- Set the multimeter to VDC
- Turn the ignition ON
- Measure the voltage
Is the voltage drop > 1V?
Yes: Check connector C31A, C31B (if installed) and the wire between junction box and FPDM , replace or repair them as necessary
No: GO to PINPOINT TEST E .