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1. Ask the customer about the malfunction. Ask what it feels like, what it sounds like, etc. Then ask about driving conditions,weather, frequency of occurrence, and 2. Determine the conditions from the customer's responses. Typically, almost all intermittent malfunctions occur from conditions likevibration, temperature and/or moisture change, 3. Use the simulation test In the cases of vibration or poor connections, use the simulation tests belowto attempt to duplicate the customer's 4. Verify that the intermittent malfunction is eliminated. Repair the malfunctioning part and try to duplicate the condition(s) againto verify that the intermittent malfunction has • Shake the connector up-and-down, right-and-left. • Shake the wiring harness up-and-down, right-and-left. • Vibrate the part or sensor. SERVICE POINTS IN INSPECTING A BLOWN FUSE • Harness being crushed by the vehicle body. • Damage to the outer casing of the harness due to wear or heat. • Water getting into the connector or circuitry. • Human error (mistakenly shorting a circuit, etc.). INSPECTING THE MFI SYSTEM 1. Engine is hard to start or does not start at all 2. Unstable idle 3. Poor driveability ON-BOARD DIAGNOSTICS • Diagnostic trouble codes are set as follows: After the PCM first detects a malfunction, a diagnostic trouble code is recorded when the engine is restarted and the • Erasing diagnostic trouble codes: After recording the diagnostic trouble code, if the PCM does not re-detect the malfunction for 40 driving cycles, the - When driving conditions (engine speed, engine coolant temperature, etc.) are identical to those when the malfunction was first recorded. - When the PCM does not re-detect the malfunction for 80 driving cycles. A "driving cycle" is complete as soon as the vehicle goes into closed-loop operation. • Catalyst • Fuel system • Air flow sensor (MAF sensor) • Intake Air Temperature Sensor (IAT sensor) • Engine Coolant Temperature Sensor (ECT sensor) • Throttle Position Sensor (TPS) • Front Oxygen Sensor • Rear Oxygen Sensor Heater • Rear Oxygen Sensor • Front Oxygen Sensor Heater • Injector • Misfire • Crankshaft Position Sensor (CKP sensor) |