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Electronic Ignition System Diagnosis

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

Ignition voltage is supplied to the ignition coil. The engine control module (ECM) provides an ground for the ignition coil control circuits. When the ECM removes the ground path of the ignition primary coil, the magnetic field produced by the coil collapses. The collapsing magnetic field produces a voltage in the secondary coil which ignites the spark plugs. The sequencing and timing are controlled by the ECM. The ignition coil consist of the following circuits:

    • An ignition circuit
    • The ignition coil 1 and 4 control
    • The ignition coil 2 and 3 control

Diagnostic Aids

The mounting bracket for the coil assembly provides the ground for the ignition coils. Ensure the mounting bolts are torqued to the correct specification.

Reference Information

Schematic Reference

Engine Controls Schematics : Siemens ECM - LPG with LCP → Siemens ECM - Gas without FX3 or LCP → Delphi ECM - FX3

Connector End View Reference

Component Connector End Views

Description and Operation

Electronic Ignition System Description

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

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 K35 ignition coil module is correctly installed.
    • The proper firing order.
    • The proper spark plug type.
    • The proper spark plug gap and torque.
    • Spark plug wires are in good condition.
    • Refer to Ignition System Specifications and Spark Plug Inspection .

Circuit/System Testing

    Note: Do not perform this diagnostic procedure if you were not sent here from a misfire DTC or the Engine Cranks But Does Not Run diagnostic.

  1. Ignition OFF, disconnect the harness connector at the K35 ignition coil module.
  2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal B and ground.
    3. ⇒If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse F2UB is open, test all components connected to the ignition circuit and replace as necessary.
  3. Ignition OFF, test for less than 2 Ω between the ignition circuit terminal B and the fuse F2UB.
    4. ⇒If greater than the specified range, repair the ignition circuit for high resistance.
  4. If all circuits test normal, test or replace the K35 ignition coil module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Ignition Coil Replacement
    •  Control Module References for replacement, setup, and programming.
   


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