1988 Cadillac Seville BaseFACTORY OEM SERVICE PROCEDURE

Notes on Intermittents

To diagnose intermittent set/coast function, turn cruise control dash switch to "ON" position and backprobe ECM pin "B4" with a voltmeter to ground. Pin "B4" should show 12 volts with "SET/COAST" switch depressed and zero volts with "SET/COAST" switch released. Cycle switch while manipulating wiring and connectors.

Fig 1: ECM Input Code EI80, Cruise Control Set/Coast Input
G57364
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:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.