Fuel Pressure Regulator Valve N276, Checking

Special tools and workshop equipment 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 

-- Observe safety precautions. Refer to SAFETY PRECAUTIONS 

-- Observe Clean Working Conditions. Refer to CLEAN WORKING CONDITIONS 

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

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: 1 to 5 Ω (at approx. 20° C)

If the specified value was not obtained:

-- Replace the Fuel Pressure Regulator Valve -N276-.

If the specified value was obtained:

Checking voltage 

-- Start the engine.

-- Using a multimeter, check the Fuel Pressure Regulator Valve -N276- electrical connector terminal 1 to ground 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 fuse 7 in Fuse Panel B for high resistance, a short circuit to voltage, ground, 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-. Refer to the Repair information.

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

Specified value: 1.5 Ω Max.

If the specification was not obtained:

-- Check the wiring for an open, high resistance or short circuit to voltage or ground.

-- 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. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .

-- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to READINESS CODE .

If the DTC does return, no malfunction is detected in the wiring and the voltage supply is OK:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the Repair information.

-- 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. 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 .