Fuel Pump Electrical, Testing

Diagnostic Procedures

Fuel Pump Electrical, Testing

Special tools, testers and auxiliary items required

• Multimeter.

• Diode test lamp

• Electrical connector test lead set.

Test conditions

• Battery voltage at least 12.5 V

• Fuel Pump Fuse OK.

• Fuel Pump Control Module (J538) OK.

• Low Fuel Pressure Sensor (G410) OK.

Test procedure

- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions

- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Test sequence

- Switch ignition on. Fuel pump must run for approx. 2 seconds.

- Switch off ignition.

If Fuel Pump does not start up:

- Remove the fuel delivery unit cover. Refer to the Repair Information





- Disconnect connector from Fuel Pump Control Module (J538) - 5 -.

- Switch ignition on.





- Check voltage supply between connector terminals - 3 - and - 4 - using a diode test lamp. LED must light up.

- Switch off ignition.

LED does not light up:

- Locate and repair open circuit in wiring using wiring diagram.

LED lights up (voltage supply OK):

CAUTION!
Fuel supply line is under high pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before removing hose connection consult the Repair Information for proper procedure.

- Remove high pressure in fuel system => [ Safety Precautions ] Safety Precautions.





• Press in securing ring to disengage the fuel line.

- Remove fuel supply line - 1 -, auxiliary heater fuel line - 2 -, fuel pump connector - 3 - and vent line - 4 -.





- Open locking ring using wrench (T10202).

- Check whether electrical wires between flange and Fuel Pump are connected.

If no open circuits are found:

- Fuel Pump faulty, replace fuel delivery unit. Refer to the Repair Information.