1990 Chevrolet Blazer 5.7 K, StandardFACTORY OEM SERVICE PROCEDURE

Park/Neutral Switch (P/N)

This switch is connected to transmission gear selector. The switch signals ECM when transmission is in Park or Neutral. Information from P/N switch is used by ECM for determining control of ignition timing, converter clutch and idle speed. To check function of P/N switch, perform functional check of switch. See SYSTEM/COMP TESTS article.

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.

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