Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Visual Inspection
& Component Testing >> Visual Inspection Visual Inspection CAUTION: When battery is disconnected, vehicle computer may lose memory data and Diagnostic Trouble Codes (DTCs) will be erased. Driveability problems may exist until vehicle is driven for 5-10 minutes. See TEST DRIVE. NOTE: Check for Diagnostic Trouble Codes (DTCs) before performing visual inspection. If repairs are made (example) to battery cables, the DTCs could be erased. See SELF-DIAGNOSTICS article. Perform a comprehensive visual inspection of ground connections locations. Ensure battery cable connections are Okay. Check ground cables between engine, vehicle body and negative battery are clean and tight. Repair as necessary. See GROUND CHECK. Check for leaking fuel components (fuel lines, injectors etc.), if damage is found, repair as necessary. Check vacuum hoses for breakage, blockage and proper routing. Check electrical wiring and connectors for damage and corrosion. If damage is found, repair as necessary. Ensure all engine systems not related to ECM are operating properly. Check for any Technical Service Bulletins (TSBs) that may apply. DO NOT proceed with testing unless all engine problems not related to ECM have been repaired. If DTC(s) are present, see SELF-DIAGNOSTICS article. If no DTC(s) are present check suspect component using Output Diagnostic Test Mode (if Output Diagnostic Test Mode is available for the suspect component). See OUTPUT DIAGNOSTIC TEST MODES (DTM) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS article. If Output Diagnostic Test Mode is not available for the suspect component proceed, go to SYSTEM & COMPONENT TESTING article.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.