1990 Jaguar XJ6 BaseFACTORY OEM SERVICE PROCEDURE

Fuel Pump Circuit (XJS)

  1. Turn ignition switch on. Fuel pump should run for 1-2 seconds, then stop. If fuel pump operates as specified, fuel pump circuit is okay. If fuel pump is inoperative, go to next step.
  2. Ensure inertia switch cut-out button is in the down position. Inertia switch is located on passengers side footwell on the front door pillar. If inertia switch cut-out button is in the down position, go to next step. If inertia switch cut-out button is in the up position, push button down to reset and repeat step 1).
  3. Remove connectors from inertia switch. Using an ohmmeter, check for continuity across switch terminals. Continuity should exists. With cut-out button in the up position, no continuity should exists. If inertia switch operation is as specified, push cut-out button in the down position and go to the next step. Replace inertia switch if operation is not as specified.
  4. Using a jumper wire, ground fuel pump relay terminal No. 85. Relay is located inside trunk behind right side trim panel next to ECU. Fuel pump relay is Silver with a Yellow/Black connector.
    NOTE: Fuel pump relay and main relay terminal identification is stamped on each relay case.
  5. Ensure voltage at fuel pump relay terminal No. 30 (Brown wire) and main relay terminal No. 30 (Brown wire). Battery voltage should be present at each terminal. If battery voltage is present go to next step. If battery voltage is not present, repair open in Brown wire between relay(s) and battery junction block. Junction block is located below battery.
  6. Turn ignition switch on. Measure voltage at main relay terminal No. 86. Main relay (Silver with Red stripe) is located next to fuel pump relay. If battery voltage is present, go to next step. If battery voltage is not present, check for open in White wire between ignition switch and inertia switch or White/Orange wire between inertia switch and terminal No. 86. Repair wire as necessary.
  7. Measure voltage at main relay terminal No. 87. If battery voltage is present, go to next step. If battery voltage is not present, replace main relay.
  8. Measure voltage at fuel pump relay No. 86. If battery voltage is present, go to next step. If battery voltage is not present, repair open in wire between main relay terminal No.87 and fuel pump relay terminal No. 86.
  9. Measure voltage at fuel pump relay terminal No. 87. If battery voltage is present, go to next step. If battery voltage is not present, replace fuel pump relay.
  10. Measure voltage at fuel pump Brown/Gray wire. If battery voltage is not present, repair open in Brown/Grey wire between fuel pump and fuel pump relay. If battery voltage is present and fuel pump ground connections are good, replace fuel pump.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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