Diagnosis of No-Spark Fault in EFI Vehicles' High-Voltage System?
1 Answers
High-voltage no-spark fault diagnosis and troubleshooting: 1. First, eliminate loose external wire connection faults. 2. Turn on the ignition switch without starting, observe the malfunction indicator lamp on the dashboard. If the lamp is on, it indicates normal ECU power supply; otherwise, inspect the power circuit. 3. Read fault codes. If present, repair components according to the fault codes. Possible causes include interrupted ECU power supply, absence of NE signal during startup, or missing IGT/IGF ignition control signals. 4. If no fault codes are present, it indicates normal operation of the ECU, induction coil, and electronic ignition module. The fault may lie in the high-voltage coil, distributor rotor, or distributor cap. 5. Use a multimeter to test primary and secondary resistances of the ignition coil. If normal, the fault likely exists in the distributor rotor or cap. Verification of repair effectiveness: Start the engine and vary its speed across medium and high operating ranges. Smooth engine operation with responsive acceleration confirms successful fault resolution.