Fuel Injector, Checking

The following test procedure is used to diagnose Fuel Injectors -N30, N31, N32, N33, N83, N84-.

Special tools and workshop equipment required 

• Multimeter.
• Diode test lamp.
• Wiring diagram.

Test requirements 

• Fuse -SB6- 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 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 

-- 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 faulty Fuel Injector --.

If the specified value was obtained:

Checking activation and wiring 

-- Connect a diode test lamp to the electrical harness connector terminals 1 and 2 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:

If the specified value was Not obtained:

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 the Repair Information.

-- Using a multimeter, check the Fuel Injector -- electrical harness connector terminals to the Engine Control Module (ECM) -J623- electrical harness connector T121 terminals for resistance.

Component	Fuel Injector -- electrical harness connector terminals	Engine Control Module (ECM) -J623- electrical connector T121 terminals or test box sockets	Motronic Engine Control Module (ECM) Power Supply Relay -J271- electrical connector terminal
Cylinder 1 Fuel Injector -N30-	1	---	87
	2	96	---
Cylinder 2 Fuel Injector -N31-	1	---	87
	2	112	---
Cylinder 3 Fuel Injector -N32-	1	---	87
	2	88	---
Cylinder 4 Fuel Injector -N33-	1	---	87
	2	113	---
Cylinder 5 Fuel Injector -N83-	1	---	87
	2	97	---
Cylinder 6 Fuel Injector -N84-	1	---	87
	2	89	---

Specified value: 1.5 Ω Max.

If the specification is Not obtained:

-- Check the wiring for an open circuit, high resistance, a short circuit to each other, 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 found 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 returns, no malfunction is found in the wiring and the voltage supply was OK:

-- Replace the 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 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 .