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 MANUALSCHEVROLET1987HI-CUBE 6.2 J, 400/M40REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 24 (ENGINE CONTROLS - TESTS W/CODES - 6.5L DIESEL)DTC 71 - SET/COAST SWITCH FAULTDIAGNOSTIC AIDS

1987 Chevrolet Hi-Cube 6.2 J, 400/M40

Diagnostic Aids

1987 Chevrolet Hi-Cube 6.2 J, 400/M40SECTION Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

Check for the SET/COAST switch stuck in the engage position or for a short to voltage in the set/coast request signal circuit.

Fig 1: DTC 71 Schematic ("C" & "K" Series) Set/Coast Switch Fault

RENDER: 1.0x

NO RELATED

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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.