Fuel Pump Electrical, Testing

Special Tools And Workshop Equipment Required 

• multimeter.
• Electrical connector test lead set.

Test conditions

• Battery voltage 12.5 V.
• Fuse -27- in Fuse Panel C is OK.
  Fig 1: Identifying Fuse Holder In Instrument Panel

  Courtesy of AUDI OF AMERICA, LLC
• Fuel filter OK.
• Ignition switched off.

Test procedure

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK

Start diagnosis

-- Remove rear seat bench. Refer to appropriate service information.

-- Remove the Fuel Pump Control Module from the retaining clips on the floor sealing cover.

-- Disconnect the electrical harness connector -arrow- from the Fuel Pump Control Module.

-- Connect the multimeter ground lead to terminal -6- of the Fuel Pump Control Module harness connector.

-- Connect the multimeter positive lead to terminal -1- of the Fuel Pump Control Module harness connector.

-- Turn the Ignition key to the ON position.

-- The meter should read within 1 volt of battery voltage.

-- If voltage is below specification, locate wiring fault in ground or power circuit. Refer to wiring diagram for location.

-- If voltage is OK, connect multimeter positive lead to terminal -3- of the Fuel Pump Control Module harness connector. The ground lead remains on terminal -6-

-- Crank the engine and note voltage displayed on multimeter during crank. Voltage should be within 2.5 volts of battery voltage.

-- If voltage is below specification, locate wiring fault in the power circuit. Refer to wiring diagram for location.

-- If voltage is OK, connect multimeter positive lead to terminal -2- of the Fuel Pump Control Module harness connector. The ground lead remains on terminal -6-

-- Crank the engine and note voltage displayed on multimeter during crank. Voltage should be 3.2 volts (+/-.4)

-- If voltage is below specification, check circuit from Fuel Pump Control Module to ECM for open, short or high resistance and repair as necessary. If no circuit fault is found, replace ECM.

-- If voltage is OK, reconnect the wiring harness to the Fuel Pump control Module.

Test procedure for Fuel Pump Control Module

-- Remove the floor sealing cover to access the Fuel Delivery Unit (fuel pump).

-- Disconnect the harness connector from the Fuel Delivery Unit.

-- Connect the multimeter positive lead to terminal -1- of the Fuel Delivery Unit harness connector.

-- Connect the multimeter ground lead to terminal -5- of the Fuel Delivery Unit harness connector.

-- Crank the engine and note voltage displayed on multimeter during crank. Voltage should be within 2.5 volts of battery voltage.

-- If voltage is below specification, replace the Fuel Pump Control Module.

-- If voltage is within specification, replace the Fuel Delivery Unit (Fuel Pump). Refer to appropriate service information.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .