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.
Class 2 Serial Data Line System Check: Testing
1997 Cadillac Seville SLSSECTION Testing
- Turn ignition switch to ON position. Connect scan tool. Attempt to establish communications with PZM. If communication cannot be established, go to next step. If communication can be established, record any DTCs that may be present. See appropriate TESTS W/CODES article in ENGINE PERFORMANCE section.
- Using scan tool, attempt to establish communications with another system on Class 2 serial data line. If communication cannot be established, go to CHART A, SCAN TOOL WILL NOT COMMUNICATE. If communication can be established, check for poor connection at PZM 24-pin connector C1 terminals B3 (Orange wire) and A12 (Black wire). If circuits are okay, replace PZM.
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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.