Fuel Pressure Regulator Valve N276, Checking

Fuel Pressure Regulator Valve N276, Checking

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements
- Fuse SB33 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. Preliminary Check

Start diagnosis
- Remove the engine cover with air filter.

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 degrees C)

If the specified value was not obtained:
- Replace the Fuel Pressure Regulator Valve N276.

If the specified value was obtained:

Checking voltage
- Crank the engine.







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

Specified value: battery voltage.
- Switch the ignition off.

If the specified value was not obtained:
- Check the wiring from the Fuel Pressure Regulator Valve N276 electrical connector terminal 1 to the Motronic Engine Control Module (ECM) Power Supply Relay 2 J670 socket 2/87 for a short circuit to Battery positive (+), Ground (GND), or an open circuit.
- 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.







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

Fuel Pressure Regulator Valve Motronic Engine Control Module
N276 electrical harness (ECM) J623 electrical harness
connector terminal connector T60 terminal or test box socket
2 19

Specified value: 1.5 Ohms Max.

If the specification was not obtained:
- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).
- 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:
- Erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory.
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:
- Replace the Motronic Engine Control Module (ECM) J623.
- Assembly is performed in the reverse of the removal.

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

1. Check the DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of Diagnosis