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 MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 59 (ENGINE CONTROLS SELF-DIAGNOSTICS - 4.3L)DIAGNOSTIC TESTSDTC P0300-P0306: ENGINE MISFIRE DETECTEDCONDITIONS FOR RUNNING DTC
1999 GMC Forward Control 5.7 R, Automatic
Conditions For Running DTC
1999 GMC Forward Control 5.7 R, AutomaticSECTION Conditions For Running DTC
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Sonoma, 2002 GMC Safari, 2002 GMC Jimmy, 2002 Chevrolet S10 Pickup, and 2002 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
If start-up ECT is less than 20°F (7°C), misfire detection is delayed until Engine Coolant Temperature (ECT) is more than 70°F (21°C). If start-up ECT is more than 20°F (7°C), misfire detection begins after a 5 second delay.
- DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0128, P0335, P0336, P0341, P0343, P0500, P0502, P0503, P1114, P1115, P1121, P1122, P1220, P1258, P1336, or P1345 are not set.
- The fuel level is more than 10 percent.
- Then engine speed is between 450-5000 RPM.
- The system voltage is between 11-16 volts.
- The Throttle Position (TP) is steady within 2 percent for 100 ms.
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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.