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.
1999 Cadillac Seville SLSFACTORY OEM SERVICE PROCEDURE
Data Link Communications System Check
- Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. If scan tool turns on, go to next step. If scan tool does not turn on, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 SERIAL DATA LINE .
- Attempt to establish communication with class 2 serial data components. Scan tool should communicate with class 2 components. If scan tool does not communicate, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 SERIAL DATA LINE .
Factory Service Tools
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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.