Ignition Coil: Testing and Inspection
Diagnostic Procedures
Ignition Coil with Power Output Stage, Checking
The following procedure is used to diagnose all Ignition Coils with Power Output Stage.
Special tools, testers and auxiliary items required
• Multimeter.
• Diode test lamp.
• Wiring diagram.
Test requirements
• The Ignition Coils with Power Output Stage ( N70, N127, N291, N292, N323) fuses OK.
• The Motronic Engine Control Module (ECM) Power Supply Relay (J271) OK.
• The Engine Speed (RPM) Sensor (G28) OK.
• The Camshaft Position (CMP) Sensor (G40)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.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check
Start diagnosis
- Remove the engine cover. Refer to the Repair Information.
- Remove the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323) electrical harness screws.
- Disconnect the ignition coil electrical harness connectors from the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323).
Checking ground supply
- Using a test lamp connected to Battery Positive, check terminals 2 and 4 of the Ignition Coils with Power Output Stage ( N70, N127, N291, N292, N323). The test lamp should be ON for each terminal check.
If the test lamp was Not ON during a terminal check:
- Check the circuit for an open or high resistance.
- Check the wiring connection for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring or connection.
If the test lamp was ON:
Checking voltage supply
- Switch the ignition ON.
- Using a multimeter, check the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323) electrical harness connector terminal 1 to ground for voltage.
Specified value: Battery voltage.
- Switch the ignition OFF.
If the specified value was Not obtained:
- Check the Ignition Coil electrical harness connector terminal 1 through fuse S130 to the Motronic Engine Control Module (ECM) Power Supply Relay (J271 ) for an open circuit.
- Check the wiring connection for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection and replace fuse if blown.
If the specified value was obtained:
Checking activation
CAUTION!
Do not touch the Ignition Coils connecting parts or adapter cables during the following test.
- Disable the power supply to the Fuel Injectors ( N30, N31, N32, N33, N83) by removing Fuse S229.
- Using a diode test lamp connected to ground, check the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323 ) electrical harness connector terminal 3 of each coil.
- Operate the starter.
The LED should blink.
- Switch the ignition OFF.
If the LED blinked and the voltage was OK:
- Replace the faulty Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323) Refer to the Repair Information.
If the LED did Not blink:
Checking wiring
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) ( J220). Refer to the Repair Information.
- Using a multimeter, Check the Ignition Coil electrical harness connector to the Motronic Engine Control Module (ECM) ( J220) electrical harness connector T121 for an open circuit.
Specified value: 1.5 ohms Max.
If the specified value was Not obtained:
- Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground.
- Check the wiring connection for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If the wiring was OK and the LED did not blink:
- Replace the Motronic Engine Control Module (ECM) (J220). Refer to the Repair Information.
- Connect the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323) electrical harness connectors to the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323).
- Install the Ignition Coils with Power Output Stage (N70, N127, N291, N292, N323) electrical harness screws.
- Install the engine cover. 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 ] Diagnostic Modes 01 - 09.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.