Description

Fig. 75 Transmission controlled spark timing control system.:

NOTE: Refer to Fig. 75 for typical spark timing control systems. Complete system schematics are located in the "Vacuum Hose Routing" section.


The spark timing control system is used on California models and is designed to control distributor vacuum advance in order to reduce HC and NOx emissions. A thermal vacuum valve in the system detects coolant temperature and, by means of wax expansion, opens or closes the line from the air cleaner.