Spark Plug Switching Control System: Description

The spark plug switching control system is designed to change the ignition system from 2-plug ignition to 1-plug ignition during heavy load driving in order to reduce engine noise. On automatic transmission vehicles, the system also functions to advance ignition timing by a specified value during 1-plug ignition.

On 1986 1/2 Pickup, ignition timing is controlled corresponding to engine operating conditions by the ECCS control unit. Optimum timing for all engine conditions has been programmed into the ECCS control unit.

Signals used to determine ignition timing are cylinder head temperature, throttle valve switch, engine RPM, engine load, engine crank angle, etc. The signal from the ECCS control unit is sent to the power transistor of the ignition coil to control the ignition timing. Detonation sensor monitors knocking condition and transmits the signal to the ECCS. After receiving the signal, the control unit retards ignition timing to avoid excessive knocking.