Spark Timing Control (STC) System

1. Ensure that vacuum hoses are properly connected and that distributor vacuum controller functions properly.
2. Install timing light.
3. Check timing with engine cold and shift lever in neutral for manual trans mission or "N" or "P" for automatic transmission.
4. Ensure that timing changes if shift lever is moved to any other position.
5. Ensure that timing does not change from position reached in step 4 when needle of water temperature gauge reaches middle of gauge, regardless of position of shift lever.
6. If timing changes in step 5, check that neutral switch and inhibitor switch emit electrical signals. If not replace defective switch.
7. If timing changes in step 5 and both neutral and inhibitor switches emit electrical signals, test water temperature switch, vacuum switching valve and thermal vacuum valve.