Contents: The engine does not start ⬇ Misfires ⬇
Since the low voltage circuit of the ignition system is controlled electronically, it is more reliable than other systems. Any damage that occurs in the low voltage circuit is most likely caused by broken or disconnected wiring or poor contact. However, the high voltage circuit is of the usual type and the probable damage is listed in the following points. There are two main signs that indicate ignition failure. The engine does not start or fires, or the engine is difficult to start and misfires.
The engine does not start
1. If the starter fails to crank the engine, check the battery and starter as described in Section 12.
2. Disconnect the high-voltage wire from any spark plug and bring the end of it approximately 5 mm away from the cylinder head using well-insulated pliers. Quickly turn the engine with the starter, there should be a uniform blue spark. If so, remove the spark plug and adjust the gap as described in Chapter 9.
3. If there is no spark, disconnect the high tension center lead from the distributor cap and check for ignition spark as described in step 2. If spark now appears, check the distributor cap, distributor rotor, and high tension leads as described in Chapters 3 and 10.
4. If there is no spark, check the resistance of the main high-tension wire as described in Chapter 10, replace as necessary. If the wiring is OK, check that all wiring and multi-pin plugs are securely fastened.
5. Check the ignition coil as described in Chapter 6.
6. If the above checks do not reveal any damage and there is still no spark, the control unit may be faulty. Consult your GM dealer for further testing or replace with a new one.
Misfires
7. If there are regular misfires, start the engine and set the idle speed to fast. Remove the high-tension wire from each spark plug and listen for a change in engine operation.
8. If no change in engine operation is noted when disconnecting the high-voltage wire from any spark plug, then this circuit is defective. When removing the wiring from one of the good cylinders, misfiring will be indicated.
9. Remove the high-tension wire from the end of the defective spark plug and hold it approximately 5 mm from the cylinder head. Restart the engine. If the spark is quite strong and regular, the fault is in the spark plug.
10. The spark plug may be loose, the insulation may be cracked, or the gap may be incorrect. Replace the plug or set the proper gap, then recheck.
11. If there is no spark at the end of the wire, or it is weak and intermittent, check the high-tension wire from the distributor to the spark plug. If the insulation is cracked, or the resistance is incorrect, replace the wiring. Check the connection on the breaker-distributor cover.
12. If there is still no spark, check the condition of the distributor cap. Replace it if necessary.
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