Transmission Spark Delay Timing Control: Description

System is used on models with transistorized dual ignition timing system. This system consists of an igniter and an overdrive (5th gear) switch. Igniter controls ignition timing, such as advance or retard. Ignition timing retards when overdrive switch is on. By retarding timing when transmission is in any gear except overdrive (5th), oxides of nitrogen (NOx) emissions are reduced. When 5th gear is selected, switch is off and ignition timing is advanced.