Ignition Coil: Testing and Inspection
Ignition Coil with Power Output Stage, Checking
The following procedure is used to diagnose Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323, N324).
Special tools, testers and auxiliary items required
• Multimeter.
• Diode test lamp.
• Wiring diagram.
Test requirements
• The Engine Control Module (ECM) (J623) fuses OK.
• Engine Control Module (ECM) Power Supply Relay (J363) OK.
• Engine Speed (RPM) Sensor (G28) OK.
• Battery voltage at least 12.5 V.
• 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.
Test procedure
- Perform a preliminary check to verify the customer's complaint. Refer to => [ Preliminary Check ] Preliminary Check.
• The ignition coils and power output stages are one component and cannot be replaced individually.
Start diagnosis
- Remove the front engine cover - arrows -.
- Remove the rear engine cover - arrows -.
Cylinder bank 1 (right):
- Remove the air duct screws - arrows -.
- Remove the air ducts - 1 - and - 2 -.
- Remove the check valve - 1 - from the air duct hose.
- Loosen the hose clamp - 2 -, release the retaining clips - arrows -, and remove the air duct hose.
- Disconnect the electrical harness connectors at the Engine Coolant Temperature (ECT) Sensor (G62) - 1 -, Intake Manifold Flap Change-over Valve (N239) - 2 -, and the Intake Manifold Tuning (IMT) Valve Position Sensor (P2076) (G513) - 3 -.
- Disconnect the electrical harness connectors from the following:
Camshaft Adjustment Valve 1 (exhaust) (N318) - 1 -
Camshaft Adjustment Valve 1 (N205) - 2 -.
Camshaft Position (CMP) Sensor (G40) - 3 -.
Intake Manifold Runner Position Sensor (G336) - 4 -.
Camshaft Position (CMP) Sensor 3 (G300).- 5 -
- Remove the screws - arrows - and disconnect the electrical connections at the ignition coils.
Cylinder bank 2 (left):
- Remove the screw - arrow - retaining the coolant reservoir.
- Disconnect the electrical connector from Engine Coolant Level (ECL) Warning Switch (F66) at the bottom of the coolant reservoir and set aside the coolant reservoir with the coolant hoses - 1 - and - 2 - connected.
- Disconnect the electrical connector from the high pressure fuel pump - 2 -.
- Disconnect the electrical harness connectors from the following:
Camshaft Position (CMP) Sensor 2 (G163)- 1 -
Camshaft Adjustment Valve 2 (N208)- 2 -
Camshaft Adjustment Valve 2 (exhaust) (N319)- 3 -
Camshaft Position (CMP) Sensor 4 (G301)- 4 -
- Remove the screws - arrows - and disconnect the electrical connections at the ignition coils.
Checking voltage supply
- Using the Diode test lamp, check the following wiring connections for voltage according to the wiring diagram:
The LED must light up.
Switch the ignition off.
If the LED does not light up:
- Using a Multimeter , check the following wire connections for an open circuit according to wiring diagram:
Specified value: 1.5 ohms max.
If specified value is not obtained:
- Repair wiring.
- Switch the ignition on.
- Using a Multimeter , check the following wire connection for voltage according to wiring diagram:
Specified value: Battery voltage
- Switch the ignition off.
If the specified value is not obtained:
- Repair wiring.
If the specified value is obtained:
Checking activation of power output stages
- Remove the rubber seal - 1 - from the plenum chamber cover.
- Remove the plenum chamber cover - 2 -.
- Using a screwdriver, remove the wiper arms caps - arrows -.
- Loosen the wiper arm nuts - arrows - several turns.
- Loosen wiper arms by gently rocking.
- Remove wiper arm nuts and wiper arms.
- Remove the screws - arrows - retaining the cowl grill - 1 -.
- Remove the cowl grill from the windshield.
- Remove the screws - arrows - and electronics box cover from the electronics box.
- Remove the Engine Control Module (ECM) Power Supply Relay (J363) from the relay carrier in the electronics box.
- Using a Multimeter , check the following for resistance:
- Check the wiring connection from the power supply relay carrier position 3 (wiring harness connector), terminal 2 to the ignition coil wiring harness connector terminal 1.
Specified value: 1.5 ohms max.
If specified value is not obtained:
- Repair the wiring.
If the specified value is obtained:
- Replace the relevant ignition coil.
• Fuel must not be injected during the test to avoid damaging the catalytic converter.
- Disconnect the fuel injector wiring harness electrical connector - 1 -.
- Using a diode test lamp, check the Ignition Coil electrical harness connector terminals 2 to 3 for voltage.
- Operate the starter briefly.
The LED must blink (brief blink signal).
- Switch the ignition off.
If the LED blinks:
- Replace the relevant, ignition coil with power output stage.
If the LED does not blink:
If the manufacturers test box is being used, perform the following step.
- Connect the Test Box 105 Pin (VAG1598/42) with Adapter Cable (1598/39-1).
If the manufacturers test box is not being used, perform the following step.
- Remove the Engine Control Module (ECM) (J623). Refer to=> [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Using a Multimeter , check the following wire connections for an open circuit according to wiring diagram:
Specified value: 1.5 ohms max.
If the specification is not obtained:
- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.
If no malfunctions are found in the wiring:
- Replace the Engine Control Module (ECM) (J623). Refer to=> [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
Assembly is performed in the reverse order of removal, note the following:
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 ] Diagnostic Mode 03 - Read DTC Memory.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.