Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1987STEP VAN P20, 7.4 W, AUTOMATIC, 400/M40REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 26 (ENGINE CONTROLS - SYSTEM/COMPONENT TESTS - 6.5L DIESEL)FUEL SYSTEMINHIBIT SWITCH (BLACK CAP)
1987 Chevrolet Step Van P20, 7.4 W, Automatic, 400/M40
Inhibit Switch (Black Cap)
1987 Chevrolet Step Van P20, 7.4 W, Automatic, 400/M40SECTION Inhibit Switch (Black Cap)
WARNING: This page does not describe the selected car, but rather 20 other vehicles, including the 1994 GMC Yukon, 1994 GMC Vandura Special, 1994 GMC Vandura, 1994 GMC Suburban, and 1994 GMC Rally Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
- Remove connector from inhibit switch when engine temperature is less than 100°F (38°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 one ohm on meter.)
- Test terminals for continuity to ground with a test light or ohmmeter on high scale. Light should be off. Meter should show greater than one megohm. Replace switch if results are not as specified.
- Disconnect plug from switch terminals when engine temperature is greater than 125°F (52°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 one megohm on meter). Replace switch if it is closed. When installing replacement switch, tighten to 17 ft. lbs. (23 N.m).
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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.