Ignition Coil

The ignition coil has a built-in power transistor which amplifies the ignition signal from the ECU. This amplified signal turns the ignition primary circuit on and off, inducing high voltage in the secondary coil windings. The coils primary circuit should have a resistance measurement of 0.84-1.02 ohms. Secondary resistance should be 8000-12,000 ohms. Insulation resistance between the primary terminal and case should be greater than 10,000 ohms. When measuring coil resistance, a very low resistance reading indicates a short circuit.