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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSGMC1991C 1500 TRUCK 2WD V6-262 4.3LREPAIR AND DIAGNOSISA L L DIAGNOSTIC TROUBLE CODES ( DTC )
1991 GMC C 1500 Truck 2WD V6-262 4.3L
A L L Diagnostic Trouble Codes ( DTC )
1991 GMC C 1500 Truck 2WD V6-262 4.3LSECTION A L L Diagnostic Trouble Codes ( DTC )
Testing and Inspection- Diagnostic Trouble Code Descriptions
- Manufacturer Code Charts
- Related Tests, Information and Procedures
- A Charts
- C Charts
- Engine Control Module (ECM)
- Chart C-1A Park/Neutral Switch Diagnosis
- Chart C-1B Crank Signal Diagnosis
- Chart C-1D Manifold Absolute Pressure (MAP) Output Check
- Chart C-2 Idle Air Control (IAC) System Check
- Chart C-4B Ignition System Check
- Chart C-5 Electronic Spark Control (ESC) System Check
- Chart C-6C Air Management Check (EAC Valve)
- Chart C-7 EGR System Check (Under 8500 GVW)
- Chart C-8 Trans Converter Clutch (TCC) (Under 8500 GVW)
- Chart C-8B Manual. Trans. Shift Light Check Below 8500 GVW
- Chart C-10A A/C On Signal Diagnosis Man Trans
- ECM QDR Check Procedure
- Powertrain Control Module (PCM)
- Engine Control Module (ECM)
RENDER: 1.0x
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.