Diagnostic Instructions
Circuit/System Description
Ignition 1 voltage is supplied to the ignition coil. The engine control module (ECM) provides a ground for the ignition coil (IC) 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:
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. Refer to
Fastener Tightening Specifications.
Reference Information
Schematic Reference
Engine Controls Schematics
Description and Operation
Electronic Ignition (EI) System Description
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
Important: 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.
- Ignition OFF, disconnect the harness connector at the ignition coil.
- Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal B and ground.
⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected
to the ignition 1 voltage circuit and replace as necessary. |
- Ignition OFF, test for less than 2 ohms of resistance between the ignition 1 voltage circuit terminal B and the fuse.
⇒ | If greater than the specified range, repair the ignition 1 voltage circuit for high resistance. |
- If all circuits test normal, test or replace the ignition coil.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Ignition Coil Replacement