General information
All components of the power supply system are highly reliable. Most failures are usually related to poor quality of electrical wiring connections. Breakdowns of high-voltage electrical wiring most often occur due to contamination, moisture, or damage to the integrity of the insulation. Before you finally decide that any of the system components is out of order, carefully check the condition of the electrical wiring of the corresponding circuit.
The authors of this Manual do not recommend checking the condition of the high-voltage wiring using such a popular method as disconnecting the wires from the spark plugs and bringing the terminal tip close to the block surface - such a procedure is fraught with not only electric shock, but also with failure of the control module or ignition coil. If the stability of engine speed is disturbed, do not disconnect the high-voltage wires from the spark plugs!
The following checks should be performed in case of obvious malfunctions, such as starter failure or misfiring. Some malfunctions are not so obvious and may not manifest themselves at all due to the automatic transition of the control system to emergency operation mode. Such failures usually make themselves known only indirectly (by increasing fuel consumption, disrupting the stability of idle speed, reducing the power developed by the engine, etc.), - contact car service specialists for advice.
The engine does not start
Failure to start the engine may be due to a failure of the anti-theft system immobilizer - turn off the alarm and immobilization system (see Chapter Controls and operating techniques).
1. If the engine does not turn over when the starter is engaged or turns over very slowly, check the starter and battery. Connect a voltmeter to the battery terminals and measure the voltage when the crankshaft is turned by the starter.
Do not operate the starter continuously for more than 10 seconds.
2. If the voltmeter registers a reading of 9.5 V or less, check the condition of the battery, starter and charging system components (see section Charging and starting systems of this Chapter).
3. If the engine does not start despite the starter turning it correctly, check the condition of all high-voltage components of the ignition system circuit.
4. Following the manufacturers instructions, connect the stroboscope and crank the engine with the starter - if the lamp on the stroboscope lights up, then voltage is being supplied to the spark plugs correctly. Check the condition of the spark plugs (see Chapter Vehicle settings and routine maintenance). If the lamp does not light, check the condition of the high-voltage wiring (see Chapter Vehicle settings and routine maintenance).
5. If spark formation is faulty, check the condition of the ignition coil/module by replacing it with a known good one, or by checking the resistance of the windings. If the engine starts after replacing the coil/module, do not rush to throw away the old coil - first check the condition of its contact terminals and the reliability of the electrical wiring connection to them.
6. If the coil is OK, the cause of the failure may be a malfunction of the powerful buffer output stage included in the ECM, one of the information sensors of the engine management system, or some related unit. In such a situation, a corresponding diagnostic code is usually entered into the ECM processor memory - fault codes are read using special diagnostic equipment (see Chapter Engine electrical systems).
Misfires
The cause of misfires is most often a violation of the quality of the terminal connections of the wiring of the ignition coil/module or one of the information sensors.
1. Turn off the ignition and check that all ignition system connectors are securely fastened.
2. Check the condition of the high-voltage wiring - assess the reliability of the spark plug wires in the intermediate clamps, make sure that the wires do not touch the metal parts of the power unit. If the wire touches the metal and its insulation is damaged, then when the engine is running, the spark will not be supplied to the spark plug, but to the ground. If you find signs of even minor damage to the insulation of at least one wire, replace the entire set.
3. The most reliable way to check is to replace the spark plug wiring kit with a known good one.
4. Replace the wires one by one to avoid disrupting the ignition sequence. Try not to damage the insulation or connector.
5. If the high-voltage wiring is in good condition, the misfire may be caused by a coil/module failure or one of the spark plugs. Replace the spark plugs (see Chapter Vehicle settings and routine maintenance). Misfires can also be caused by a faulty or dirty crankshaft position sensor (see Chapter Fuel, exhaust and emission control systems). If the cause of the malfunction cannot be identified during independent checks, the vehicle should be taken to a service station for a complete diagnosis of the control system using special equipment (see sections On-Board Diagnostic System OBD - General Information and Using an Oscilloscope to Monitor the Operating Parameters of a Control System).
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