Warning: Due to the high voltages that are generated in the ignition system, extreme caution must always be exercised when servicing components of the ignition system. This applies not only to the ignition module/ECU, ignition coil, and high-voltage wires, but also to components such as electrical connectors, tachometer, and other monitoring equipment.
Note: This is an initial test of the ignition subsystem, which is part of the engine management system. It is one of the preliminary tests of the entire engine management system (see Chapter 6).
1. If the engine cranks but does not start, disconnect the spark plug wire from any spark plug and connect it to a calibrated tester (available at auto parts stores). Connect the tester clamp to a good ground - a bolt or metal bracket on the engine. If you cannot obtain a calibrated spark tester, then this test should be performed by a dealer. Other methods of testing (such as checking for spark by grounding the spark plug wire) are not recommended due to the risk of accidents or damage to the ignition module/ECU (see note here and in paragraph 1).
2. Crank the engine and watch the tester tip to see if reliable blue sparks appear.
3. If sparking is visible, then the spark plug is receiving sufficient voltage to ignite. Repeat the check of the remaining spark plugs to ensure that all wires are in good condition and that the voltage coil is operational. However, the spark plugs themselves may be faulty or dirty. Therefore, remove and inspect them as described in chapter 1.
4. If the spark is intermittent or absent, the spark plug wire may be faulty. Check it (see chapter 1).
5. If there is still no spark, check the ignition coil electrical connector and make sure it is clean and securely fastened. Check if battery voltage is reaching the coil (i.e. the center terminal of its electrical connector). The coil is grounded through the ECU, so do not attempt to check this. Check the coil itself (paragraph 3). Make any necessary repairs, then repeat the check.
6. The remaining system checks must be performed by dealers, since if tested incorrectly, the ignition control unit can be damaged.
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