Electronic Ignition System Diagnosis (LDK with Turbocharger)

/ 9-5 (9650) / 2010 / 2. Engine / Engine management and fuel system, 4-cyl petrol / Fault diagnosis, fault symptoms / Electronic Ignition System Diagnosis (LDK with Turbocharger)

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The ignition system uses individual ignition coil/module assemblies for each cylinder. The engine control module (ECM) controls the individual coils by transmitting timing pulses on the ignition control circuit of each ignition coil/module to enable a spark event. Each ignition coil/module has the following circuits:

•	Ignition 1 voltage

•

Ground

•	Ignition control

•	Low Reference

Diagnostic Aids

•	Depending on the location in the spliced ignition voltage circuit, a slight to moderate resistance can cause a misfire or a crank/no start concern.

•	Extended engine cranking time, will foul the spark plugs with excessive fuel and cause a crank/no start condition.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 Spark Tester

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification

Note

Verify that the engine is in good mechanical condition before continuing with this diagnostic.

•	Review the ignition system specifications and the spark plug inspection procedure to verify the following:

-

The ignition coil/modules are correctly connected

-

The proper firing order

-

The proper spark plug type

-

The proper spark plug gap and torque Refer to Ignition System Specifications (LDK with Turbocharger) .

•	If the engine will start, then observe the scan tool Misfire Current Cylinder parameters. This will indicate the affected ignition coil/modules.

Circuit/System Testing

1.	Let the ignition remain OFF for 90 seconds. Now disconnect the harness connector at the affected T8 ignition coil/module.

2.	Test for less than 5Ω between the ground circuit terminal 1 and ground.

3.	If greater than the specified range, test the ground circuit for an open/high resistance.

4.	Test for less than 5Ω between the low reference circuit terminal 2 and ground.

5.	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

6.	Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 4 and ground.

7.	If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance.

8.	Exchange the affected T8 ignition coil/module with the T8 ignition coil/module of a good cylinder.

9.	Start the engine, observe the scan tool Misfire Current Cylinder parameters.

10.	If the misfire transfers with the suspect T8 ignition coil/module, replace it.

11.	If the misfire does not transfer with the suspect T8 ignition coil/module, replace the spark plug.

Component Testing

Use the J 26792 to verify the output of each ignition coil/module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Ignition Coil Replacement

•	Spark Plug Replacement

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