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 MANUALSGMC2010SAVANA SPECIAL 4.8 AREPAIR AND DIAGNOSISENGINE MECHANICALSTARTERBATTERY, CHARGING SYSTEM AND STARTING SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURES (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DTC P0621 (GAS)CIRCUIT/SYSTEM TESTING (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)4.3L ENGINE
2010 GMC Savana Special 4.8 A
4.3L Engine
2010 GMC Savana Special 4.8 ASECTION 4.3L Engine
- 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.
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.