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 MANUALSGMC1986PICKUP C1500, 6.2 C, AUTOMATICREPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANSDIAGNOSIS - TORQUE CONVERTER CLUTCHADJUSTMENTSTHROTTLE POSITION SENSOR (CARBURETED MODELS ONLY)
1986 GMC Pickup C1500, 6.2 C, Automatic
Throttle Position Sensor (CARBURETED Models Only)
1986 GMC Pickup C1500, 6.2 C, AutomaticSECTION Throttle Position Sensor (CARBURETED Models Only)
- Ensure that engine idle speed is correct. On 2.8L engine equipped vehicles, disconnect TPS connector and jumper all 3 terminals. On all models, connect digital voltmeter from TPS connector center terminal to bottom terminal.
- Turn ignition on, DO NOT start engine. On 2.8L engine equipped vehicles, ensure that A/C is off and that throttle kicker solenoid is fully retracted. On all other models, disconnect electrical connector from idle solenoid and let throttle lever rest against idle speed screw.
- On all models, read TPS voltage. If reading is incorrect, use a 5/64" drill bit and carefully drill a hole in plug covering TPS adjustment screw. Plug is located next to TPS plunger bore. Start a No. 8, 1/2" long self-tapping screw in drilled hole turning screw in only enough to ensure good thread engagement.
- Place a screwdriver between screw head and carburetor air horn casting, pry against screw head to remove plug. With ignition on, engine stopped; turn TPS adjustment screw to obtain specified voltage. See Fig 1 and THROTTLE POSITION SENSOR VOLTAGE . After adjustment, a new plug or RTV sealant must be inserted in TPS adjustment screw hole.
THROTTLE POSITION SENSOR VOLTAGE (1)
| Throttle Position Application | Volts At Idle | |||
|---|---|---|---|---|
| Passenger Cars | ||||
| 2.8L V6 | .30 | |||
| 3.8L V6 (VIN A) | .30 | |||
| 5.0L V8 (VIN G & H) | .50-.58 | |||
| 5.0L V8 (VIN Y & 9) | .45-.47 | |||
| 5.7L V8 (VIN 6) | .45-.47 | |||
| Light Duty Trucks | ||||
| Calif. 4.3L, 5.0L & 5.7L V8 | .30-.32 | |||
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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.