Voltage Supply, Checking

Voltage Supply, Checking

Special tools, testers and auxiliary items required

• Multi-meter, for example, Multi-Meter (V.A.G 1526 D)

• Current Clamp (V.A.G 1526B/2) , or equivalent

• Test Instrument Adapter/DSO (5-pin) (VAS 5565)

Test Conditions:

• The fuses must be OK.

• Battery voltage must be a minimum of 12 volts. Connect a battery charger if necessary.

• All electrical consumers such as, for example, lights and rear window defogger, must be turned off.

- Disconnect the connector from the auxiliary fuel pump/fuel pump 2 (in-line electric fuel pump) inside the engine compartment.

- Remove the rear seat bench.

- Fold the carpet to the side or towards the front.

- Remove the cover from the fuel delivery unit.

- Turn the ignition on. The fuel pump must run audibly for approximately 2 seconds.

- Turn the ignition off.

If the fuel pump does not activate:

- Disconnect the connector from the fuel delivery unit flange.

- Connect the rest instrument adapter/DSO (5-pin) (VAS 5565) between the connectors on the cover and the flange.

- Connect the multi-meter to the test contacts - 1 and 5 - on the rest instrument adapter/DSO (5-pin) (VAS 5565).






- Connect the vehicle diagnostic tester and perform the guided function "Check Electric Fuel Pumps".

• The fuel pump now runs for 30 seconds.

- Read the voltage value on the multi-meter:

Target value = approximately the battery voltage.

If there is no voltage:

- Check activation of fuel pump relay and check the wires for an open circuit and a short circuit.

If the voltage supply is OK:

- Remove the fuel delivery unit. Refer to => [ Fuel Delivery Unit ] Fuel Delivery Unit.

- Check if the electrical wiring between the flange and fuel pump is connected and has continuity.

If no open circuits are found:

- Replace the fuel delivery unit.