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 MANUALSGMC1993JIMMY BASE, 2D UTILITY, 4.3 Z, RWD, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - V6SELF-DIAGNOSTIC TESTSCODE 39, KNOCK SENSOR CIRCUIT SHORTED - 4.3L "S" & "T" SERIES PICKUP WITH MANUAL TRANSMISSIONNOTES
1993 GMC Jimmy Base, 2D Utility, 4.3 Z, RWD, Standard
Code 39, Knock Sensor Circuit Shorted - 4.3L "S" & "T" Series Pickup With Manual Transmission: Notes
1993 GMC Jimmy Base, 2D Utility, 4.3 Z, RWD, StandardSECTION Notes
NOTE:
Test numbers refer to numbers on diagnostic chart.
- VCM applies and monitors 5 volts on knock signal circuit. This voltage should be present on sensor leads with sensors disconnected.
- Determines if wiring or knock sensor portion of the VCM's internal PROM (MEM-CAL) is faulty
- An improperly installed knock sensor can prevent knock sensor from grounding to block.
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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.