1998 Cadillac Eldorado BaseFACTORY OEM SERVICE PROCEDURE

Class 2 Serial Data Line System Check: Testing

  1. Connect scan tool. Turn ignition switch to ON position. Attempt to establish communication with PZM. If communication cannot be established, go to next step. If communication can be established, record any DTCs that may be present. For PZM DTCs, go to appropriate DTC test. For other DTCs, see appropriate section.
  2. Using scan tool, attempt to establish communication 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 Brown 24-pin connector C1, terminals B1 (Orange wire), A1 (Purple wire), A2 (Purple wire), and A12 (Black wire). See WIRING DIAGRAMS  . If circuits are okay, replace PZM. See REMOVAL & INSTALLATION.
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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.

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