1988 Cadillac Seville BaseFACTORY OEM SERVICE PROCEDURE

Notes On Intermittents

Check for NSBU switch and transmission indicator out of adjustment. Check for open or short to ground in circuit No. 434 between ECM and switch. Check for open to ground on switch pin "B".

Review snapshot data parameters stored with this code to verify failure condition. If failure condition is verified, check and repair intermittent wiring connections or sensor.

Fig 1: ECM Input Code EI74, Park/Neutral Switch Circuit
G57307
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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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.