Caution! Due to the very high voltage generated in the ignition system, its components must be serviced with extreme caution. This applies not only to the main components of the electronic ignition system, but also to all associated components, including spark plug wire leads, tachometer and other diagnostic equipment.
1. If the ignition system is not functioning properly, before diagnosing the condition of the distributor, perform the following preliminary checks:
- a) Check the condition of the battery terminal connections and the tightness of the clamps securing the wire ends to them;
- b) Check the battery condition (see Checking the battery status and replacing it), replace it if necessary;
- c) Check the external condition of the distributor and ignition coil high voltage wires and the reliability of their fastening to the terminals;
- d) If equipped, check the condition of the fuse links in the fuse box located in the engine compartment of the vehicle (see Chapter On-board electrical equipment). Replace burnt-out elements.
2. Check the spark plugs for proper spark formation. If the engine turns over but does not start, disconnect the high-voltage wire from one of the spark plugs and connect it to a special calibrated tester (ask in car accessories stores). Attach the tester clamp to a bolt or metal bracket on the engine block, thereby reliably grounding it to ground (see accompanying illustration). If you do not have a calibrated spark tester handy, disconnect the spark plug wire and, holding it with pliers with securely insulated handles, pull the rubber tip up the wire and bring the contact terminal to a well-grounded point on the block at a distance of approximately 6.4 mm. When turning the engine, a clearly visible bright blue spark should jump between the electrode and the tester body / high-voltage terminal of the wire and the ground. Crank the engine, observing the tester or wire terminal - if sufficient voltage is supplied to the spark plug, an intense bright blue spark should jump between the electrode and the tester body / wire terminal and the engine block.
- a) If the spark breaks through properly and its intensity is not in doubt, repeat the check for the high-voltage wires of the remaining spark plugs. This check allows you to confirm the serviceability of the cover and the distributor rotor, but does not exclude the possibility of failure of the spark plugs themselves, so unscrew the spark plugs and check their condition in accordance with the procedure given in Chapter Routine maintenance of this Manual description;
- b) If there is no spark, remove the distributor cap and check its condition, as well as the condition of the rotor (see Chapter Routine maintenance). If there are traces of moisture, carefully wipe the surfaces of the cover and runner with a clean dry cloth, then replace the cover and repeat the spark test;
- c) If removing moisture does not correct the situation (spark formation is still not intense enough or is absent altogether), disconnect the secondary wire of the coil from the distributor cap and connect an ignition tester to it (don't forget to connect the high voltage wires to all spark plugs). Repeat the above inspection procedure. Check the condition of the spring and the contact carbon button inside the distributor cap for signs of burnout and mechanical damage. Replace the distributor cap if necessary.
Note: If you do not have an ignition tester at hand, an alternative test of the coil wire is carried out in the same way as in the case of high-voltage spark plug wires by connecting the terminal to ground at a distance of about 6.4 mm.
Note: The vehicles covered in this manual are equipped with an ignition coil built into the distributor.
3. If normal spark formation occurs this time, then the cause of the failure lies in a faulty distributor cap, its rotor or the corresponding spark plug wires (see Chapter Routine maintenance).
4. If there is no spark formation and at this stage, proceed to check the contact connections of the primary circuit of the ignition coil - assess the condition and reliability of the terminals. Check the serviceability of the primary voltage supply to the coil from the ignition switch/lock, for which measure the voltage on the positive side of the coil (see accompanying illustration). Check the condition of the coil (see Checking the condition and replacing the ignition coil). Make any necessary corrections, then retry the test.
5. Check the condition of the ignition coil. Using an ohmmeter, measure the resistive resistance of its primary and secondary windings (see Checking the condition and replacing the ignition coil). If breaks are detected, replace the coil.
6. Check the ignition control module (ICM) for proper operation.