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ELECTRONIC ENGINE CONTROLS - ENGINE SYMPTOM DIAGNOSIS
Symptom Diagnostic Tests
General Troubleshooting Checks
• Confirm the engine Malfunction Indicator Light (MIL) is working properly.
• Confirm that there are no DTCs recorded with the X-431 Scan Tool.
• Confirm that the customer's complaint is current, and the conditions that are causing the failure are present.
Visual Inspection
• Check the fuel system for any fuel leakage.
• Check the vacuum system for any broken, kinked or incorrectly linked vacuum pipes or hoses.
• Check the intake air pipe for being jammed, leaking, or damaged.
• Check the ignition system for any broken or aging spark plug wires and verify the engine firing order is correct.
• Check the engine ground cable and verify a clean and tight connection.
• Check the sensors and actuators electrical connectors and verify good contact and tight connection.
NOTE :
Repair any of the above conditions first before continuing with symptom diagnostics.
Diagnostic Help
• Confirm there are no current engine DTCs.
• Confirm that the failure exists and the customer complaint can be verified.
• Inspect the engine, following the steps above and verify all engine features are operating properly.
• While servicing the vehicle, verify the service record, vehicle maintenance, engine compression pressures,
mechanical ignition timing and fuel conditions.
• If replacing the Engine Control Module (ECM), carry out the validation test. If the failure no longer exists, the
failure is in the ECM; if the failure still exists, reinstall the original ECM and repeat the diagnostic test.
Symptom Diagnostic Test List
Engine Cranks Normal But Will Not Start
Engine Will Not Crank
Hard Start / Long Crank Time
Fast Idle
Lack / Loss Of Power
Back Fires
Engine Poor Driveability
Low Idle / Stalls During Deceleration
Idle Speed Slow Return To Normal Idle
Chery Automobile Co., Ltd.
SYMPTOM DEFINITION
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