GM Service Manual Online
For 1990-2009 cars only

Electronic Ignition (EI)

For information on electronic ignition system, refer to. in Engine Controls .

Ignition (IC) Control Circuit

For information on the IC circuit and on ignition timing, refer to. in Engine Controls .

Ignition Timing

For information on ignition timing, refer to. in Engine Controls .

Secondary Wiring

The spark plug wiring is 7 mm (9/32 inch) in diameter. It consists of a wire wound center , insulation which gives the cable dielectric strength, a braid which functions as a strength member and a rubber jacket which provides environmental protection. The silicone spark plug boots provide a tight seal on the spark plug. Do not force anything between the boot and wiring or through the silicone jacket. Connections should be made in parallel using an appropriate adapter. The spark plug wire boots contain FHC grease as a lubricant. This lubricant will last the life of the spark plug wires. This coating is clear and has a slightly waxy feel. The coating helps prevent the silicone spark plug boot from sticking to the spark plug ceramic. This greatly reduces the effort required to remove and install the spark plug boots and spark plug wires. If silicone type lubricants are added to FHC coated spark plug boots, carbon tracking of the spark plugs may occur. During spark plug wire removal, do not pull on the spark plug wire. Pull on the spark plug boot/shield, or use a tool designed for this purpose.

Spark Plugs

Resistor type, tapered seat spark plugs are used on this engine. No gasket is used on these tapered seat spark plugs. Refer to Spark Plug Usage for spark plug type and gap size. When replacing spark plugs, use only the type specified. Normal service is assumed to be a mixture of idling, slow speed, and high-speed driving. Occasional intermittent high-speed driving is needed for good spark plug performance. It gives increased combustion heat, burning away carbon or oxides that have built up from frequent idling, or continual stop and go driving. Spark plugs are protected by insulating boots made of special heat-resistant materials, which cover the spark plug terminal and extend downward over a portion of the spark plug insulator. These boots prevent flash-over, which causes engine misfiring. Do not mistake corona discharge for flash-over, or a shorted insulator. Corona is a steady blue light appearing around the insulator, just above the shell crimp. It is the visible evidence of a high-tension field and has no effect on ignition performance. Usually it can be detected only in darkness. This discharge may repel dust particles, leaving a clear ring on the insulator just above the shell. This ring is sometimes mistakenly regarded as evidence that combustion gases have blown out between the shell and the insulator.

Ignition Switch

The mechanical key and lock cylinder switch is located in the steering column on the right-hand side. The electrical switching portion of the assembly is separate from the key and lock cylinder. Both are synchronized and work in conjunction through the action of the actuator rod assembly. For an explanation of the key and lock cylinder and the ignition switch actuator assembly, refer to steering wheel and column description in Steering Wheel and Column-Tilt.