Electronic Ignition System Diagnosis (LDK with Turbocharger)
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Electronic Ignition System Diagnosis (LDK with Turbocharger)
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Circuit/System Description
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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:
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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.
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Extended engine cranking time, will foul the spark plugs with excessive fuel and cause a crank/no start condition.
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Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
Special Tools
J 26792 Spark Tester
For equivalent regional tools, refer to
Special Tools
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Circuit/System Verification
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Note
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Verify that the engine is in good mechanical condition before continuing with this diagnostic.
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Review the ignition system specifications and the spark plug inspection procedure to verify the following:
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The ignition coil/modules are correctly connected
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The proper firing order
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The proper spark plug type
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If the engine will start, then observe the scan tool Misfire Current Cylinder parameters. This will indicate the affected ignition coil/modules.
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1.
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Let the ignition remain OFF for 90 seconds. Now disconnect the harness connector at the affected T8 ignition coil/module.
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2.
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Test for less than 5Ω between the ground circuit terminal 1 and ground.
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3.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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4.
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Test for less than 5Ω between the low reference circuit terminal 2 and ground.
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5.
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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.
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6.
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Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 4 and ground.
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7.
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If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance.
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8.
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Exchange the affected T8 ignition coil/module with the T8 ignition coil/module of a good cylinder.
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9.
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Start the engine, observe the scan tool Misfire Current Cylinder parameters.
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10.
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If the misfire transfers with the suspect T8 ignition coil/module, replace it.
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11.
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If the misfire does not transfer with the suspect T8 ignition coil/module, replace the spark plug.
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Use the J 26792 to verify the output of each ignition coil/module.
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
