Fuel Pressure Regulator Valve, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Fuel Pump (FP) Control Module -J538- OK.
• The 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 

Start diagnosis 

-- Remove the engine cover with air filter. Refer to the Repair Information.

Checking resistance 

-- Disconnect the Fuel Pressure Regulator Valve -N276- electrical harness connector -2- from the Fuel High Pressure Pump -- assembly -1-.

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

Specified value: 0.4 to 1.2 Ω (at approx. 20° C)

If the specified value was Not obtained: 

-- Replace the Fuel Pressure Regulator Valve -N276-: Refer to the Repair Information.

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 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 Engine Component Power Supply Relay -J757- (for < 2011) or Fuel Pump Relay -J49- (for 2012 and later) terminal 5 (relay pin 87) for a short circuit to Ground, high resistance or an open circuit.

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

-- If necessary, repair the wiring connection.

-- If a short was found, replace fuse also.

If the specified value was obtained: 

Checking wiring 

-- Remove the Engine Control Module (ECM) -J623-. Refer to the Repair Information.

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

Fuel Pressure Regulator Valve -N276- electrical harness connector terminal:	Engine Control Module (ECM) -J623- electrical connector T60 terminal:
2	19

Specified value: 1.5 Ω Max.

If the specified value was Not obtained: 

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

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

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained: 

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

-- Install the engine cover with air filter. Refer to the Repair Information.

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 .
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 .