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 MANUALSGMC2011SAVANA SPECIAL 4.8 AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 11 (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURES (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DTC P0621 (GAS)CIRCUIT/SYSTEM TESTING (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)4.3L ENGINE
2011 GMC Savana Special 4.8 A
4.3L Engine
2011 GMC Savana Special 4.8 ASECTION 4.3L Engine
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2010 GMC Savana Special, 2010 GMC Savana Camper Special, 2010 GMC Savana, 2010 Chevrolet RV Cutaway, and 2010 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
- Verify that a test lamp illuminates between the generator B+ terminal B X2 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Ignition OFF, disconnect the X1 harness connector at the generator.
- Ignition ON, test for less than 1 V between the generator turn on signal circuit terminal 1 and ground.
- If greater than the specified range, test the generator turn on signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Engine running, test for greater than 3.5 V between the generator turn on signal circuit terminal 1 and ground.
- If less than the specified range, test the generator turn on signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If the circuit tests normal, test or replace the generator.
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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.