Circuit Description

The Engine Control Module (ECM) provides a ground for the electronic spark timing circuit. 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 fires the spark plug.

The circuit between the ECM and the electronic ignition system ignition coil is monitored for an open circuit, short to voltage and short to ground. When the ECM detects a problem in the electronic spark timing circuit, it will set Diagnostic Trouble Code.