Impala V8-305 5.0L VIN H 4-bbl (1982)
Transmission Controlled Spark System: Testing and Inspection
NOTE: To test the SCS system, leave the distributor vacuum hose connected, ensure that engine coolant temperature is between 95° and 230° F and
proceed as follows:
1. Raise the rear wheels.
2. Start engine and shift into Drive.
3. Accelerate engine while observing timing mark on harmonic balancer.
4. Timing should advance when vehicle speed exceeds 35 mph.
No Vacuum Advance At Calibration Speed
NOTE: If vacuum advance does not occur at speeds over 35 mph, check for:
1. Reversed vacuum lines at vacuum solenoid valve.
2. Foreign matter in vacuum solenoid valve.
3. Disconnected or broken distributor vacuum line.
4. Defective vacuum solenoid valve.
5. Shorted speed sensor switch or wire.
Full Vacuum Advance At All Speeds
NOTE: If full vacuum advance occurs at all vehicle speeds, check system for:
1. Blown fuse.
2. Disconnected wire at vacuum solenoid valve.
3. Disconnected wire at speed control switch or faulty switch.
4. Faulty temperature switch.