Fuel Metering Valve 2, Checking

The following procedure is used to diagnose the Fuel Metering Valve 2 -N402- which is controlled by Motronic Engine Control Module (ECM) -J623-.

Special Tools And Workshop Equipment Required 

• Multimeter.
• Wiring diagram.

Test requirements

• The Engine Component Power Supply Relay -J757- OK.
• The Fuse -SA 4- OK.
• The fuel filter OK.
• The parking brake engaged.
• The battery voltage at least 12.5 V.
• The selector lever of automatic transmission in position "P" or "N".
• All electrical consumers switched off.
• 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

-- Disconnect the Fuel Metering Valve 2 -N402- electrical harness connector -arrow-. in l.h. high pressure pump.

Checking internal resistance

-- Using a Multimeter --, check the Fuel Metering Valve 2 -N402- terminals 1 to 2 for resistance

Specified value: 22- 30 Ω.

If the specified value was not obtained:

-- Replace the Fuel Metering Valve 2 -N402-. Refer to appropriate service information.

If the specified value was obtained:

Checking voltage

Crank the engine.

-- Using a Multimeter --, check the Fuel Metering Valve 2 -N402- electrical harness 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 Metering Valve 2 -N402- electrical harness connector terminal 1 to the Fuse (on fuse/relay panel) -SA 4- for an open circuit or a short circuit to Ground (GND).

-- 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 connections

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 Engine Control Module (ECM) -J623-. Refer to appropriate service information.

-- Using a multimeter --, check the Fuel Metering Valve 2 -N402- electrical harness connector terminal 2 to the Engine Control Module (ECM) -J623- electrical harness connector T105 for resistance.

Fuel Metering Valve 2 -N402- electrical harness connector terminal	Engine Control Module (ECM) -J623- electrical connector T105 terminal
2	85

Specified value: 1.5 Ω Max.

If the specification was not obtained:

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

-- 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:

Repair complete, Generate readiness code. Refer to READINESS CODE .

If the DTC returns and no malfunction is found in the wiring and voltage supply was OK:

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

Assembly is performed in the reverse order of the removal, note the following:

Final procedures

After 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 .