VW Passat & Audi A4 1990-2000

Fuel Pump Electrical Circuit

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DIAGNOSIS & TESTING
  1. To begin testing the fuel pump electrical circuit, first check that the battery is at a full state of charge.
  2.  


NOTE
Do NOT forget to check the condition of the fuse in the fuse box. If it is blown, the fuel pump will not receive the necessary electricity to operate.

  1. Remove the access panel from the fuel pump.
  2.  
  3. Turn the ignition key to the ON position and have a helper listen for the pump to begin running. If the system is operating correctly, the pump should run for a short period and then shut off. If the pump does not run, continue on to the following steps.
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  5. Remove the fuel pump relay and operate the pump using a remote by-pass switch. If the pump runs after performing this test, proceed to the next diagnostic step in this procedure.
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  7. Install the fuel pump relay again.
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  9. Check for proper activation of the fuel pump relay, using an appropriate circuit tester.
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  11. If the fuel pump does not run when the relay is by-passed follow the following procedures:
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    1. Remove luggage compartment floor cover.
    2.  
    3. Disconnect the fuel pump wiring connector.
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    5. Remove the fuel pump relay and install a remote starter, VAG 1348/3A, with adapter wire, to connector and battery plus (+) terminal.
    6.  

  13. Connect an LED tester, VAG 1527B (or equivalent), to outer terminal of connector, using jumper wires from test kit.
  14.  

If LED does not light up, check the circuit wiring for faults. Repair as necessary.

If LED lights up, loosen flange nut with special spanner wrench, and then check the wiring and connections between the flange and fuel pump assembly.



If no open circuit is found, the fuel pump is defective and needs to be replaced.
 

 
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