1992 GMC Pickup C2500, 2D Pickup Extra Cab, 6.5 F, AutomaticFACTORY OEM SERVICE PROCEDURE

Inhibit Switch (Black Cap)

  1. Remove connector from inhibit switch when engine temperature is less than 100Β°F (38Β°C). Inhibit switch is located in water crossover near front of engine. Set ohmmeter on low range. Test continuity across switch terminals. Switch should be closed (a reading of less than 1.0 ohm on meter.)
  2. Test terminals for continuity to ground with a test light or ohmmeter on high scale. Light should be off. Meter should show greater than 1.0 megohm. Replace switch if results are not as specified.
  3. Disconnect plug from switch terminals when engine temperature is greater than 125Β°F (52Β°C). Change ohmmeter setting to highest scale or use a self-powered test light. Test continuity across switch terminals. Test continuity from each terminal to ground. Switch should be open (test light off or high ohm reading of greater than 1.0 megohm on meter). Replace switch if it is closed. When installing replacement switch, tighten to 17 ft. lbs. (23 N.m).
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.

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