Fuel Injectors, Checking

Observe all safety precautions: SAFETY PRECAUTIONS 

View clean working conditions: CLEAN WORKING CONDITIONS 

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools and workshop equipment required 

• multimeter.
• Diode test lamp (12V).
• Wiring diagram.

Test requirements

• The Engine Speed (RPM) Sensor -G28- OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Ignition switched off.

-- Observe safety precautions.

-- Observe rules for cleanliness.

Test procedure

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

Start diagnosis

-- Remove the engine cover with air filter -1-. Refer to appropriate service manual.

-- Disconnect the Fuel Injector -- electrical harness connectors from Fuel Injectors -N30, N31, N32, N33, N83, N84-.

Checking internal resistance

-- Using a multimeter, check the Fuel Injector -- electrical terminals 1 to 2 for resistance.

Specified value: 12.0 to 20.0 Ω (at approx. 20° C)

If the specified value was not obtained:

-- Replace the malfunctioning Fuel Injector --.

Specified values: 1.5 Ω max. for wire continuity, and for circuit to ground check; Infinity or "OL" is displayed

If the specification is 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.

Checking activation and wiring

-- Connect a diode test lamp (12V) from Battery + to the injector harness connector terminal (1 for N30, 1 for N31, 1 for N32, 1 for N33, 1 for N83, or 1 for N84) of the Fuel Injector -- to be tested.

-- Operate the starter and test the activation of the Fuel Injector --.

LED should flicker.

-- Switch the ignition off.

If LED does not flicker, check for an open

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 Injector -- electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 terminals for an open circuit.

Component	Fuel Injector -- electrical harness connector terminals	Motronic Engine Control Module (ECM) -J623- electrical connector T60 terminals or test box sockets
Cylinder 1 Fuel Injector -N30-	1	33
	2	2
Cylinder 2 Fuel Injector -N31-	1	47
	2	1
Cylinder 3 Fuel Injector -N32-	1	31
	2	18
Cylinder 4 Fuel Injector -N33-	1	46
	2	3
Cylinder 5 Fuel Injector -N83-	1	32
	2	17
Cylinder 6Fuel Injector -N84-	1	48
	2	16

Specified value: 1.5 Ω Max.

If the specification is not obtained:

-- Check the wiring for an open, high resistance or short to battery 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:

-- 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 .
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 .