Fuel Pressure Regulator Valve, Checking

Fuel Pressure Regulator Valve, Checking

Special tools, testers and auxiliary items required

• multimeter.

• Wiring diagram.

Test requirements

• The Engine Component Power Supply Relay (J757) OK.

• The Motronic Engine Control Module (ECM) (J623) fuses OK.

• The fuel filter OK.

• The battery voltage at least 12.5 V.

• All electrical consumers switched off (radiator fan must NOT run during test).

• A/C switched off.

• The fuel tank at least 1/4 filled.

• The ignition switched off.

Test procedure

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

Start diagnosis

- Remove the engine cover with air filter. Refer to appropriate service manual.





Checking resistance

- Disconnect the Fuel Pressure Regulator Valve (N276) electrical harness connector - 2 -.





- Using a multimeter, check the Fuel Pressure Regulator Valve (N276) terminals 1 to 2 for resistance.





Specified value: 25 to 35 ohms (at approx. 20° C)

If the specified value was not obtained:

- Replace the Fuel Pressure Regulator Valve (N276). Refer to appropriate service manual.

If the specified value was obtained:

Checking voltage

Switch the ignition on.

- Using a multimeter, check the Fuel Pressure Regulator Valve (N276)electrical connector terminal 1 to Ground (GND) for voltage.





Specified value: battery voltage.

If the specified value was not obtained:

- Check the wiring from the Fuel Pressure Regulator Valve (N276) electrical connector terminal 1 to the Engine Component Power Supply Relay (J757) terminal 8 for a short circuit to Ground (GND), or an open circuit.

Switch the ignition off.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box.

If the manufacturers test box is not being used, perform the following step.

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service manual.

- Using a multimeter, check the Fuel Pressure Regulator Valve (N276) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 terminals for an open circuit according to the wiring diagram.









Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the wiring for a short circuit to Battery (+), or an open circuit.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service manual.

- Install the engine cover with air filter. Refer to appropriate service manual.

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 ] Scan Tool Testing and Procedures.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Scan Tool Testing and Procedures.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.