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.
Circuit/System Testing
2006 Chevrolet Suburban C2500, 6.0 USECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Generator
- Verify that the battery cable terminals are clean and tight.
- Connect a carbon pile tester to the battery.
- Start the engine and increase the engine speed to 2,500 RPM. Place the vehicle in tow/haul mode. Observe the voltage reading on the tester. The voltage should read between 12.6 - 15.0 volts.
- If not within specified range, replace the generator.
- Adjust the carbon pile tester to the specified load test output value, refer to Generator Usage .
- If less than the specified value, replace the generator.
- If equipped with an auxiliary generator, repeat this test, with the carbon pile tester's inductive pickup clamped around either generator harness.
Auxiliary Battery Charging/Isolation (TP2)
Perform this test if there is a concern with the charging of an auxiliary battery.
Do not perform this test if the vehicle is not equipped with an auxiliary battery (TP2).
- Disconnect the auxiliary battery. Refer to Auxiliary Battery Replacement (6.2L, and 6.6L) .
- Verify that there is not a fuse installed in the STUD 1 socket of the underhood fuse block. There may be a plastic plug installed in this position, instead of a fuse.
- If there is a fuse installed, remove the fuse.
- Verify that the trailer harness, or other accessory, is connected to the underhood fuse block stud 1 terminal X7-1, if desired. Verify that the connection is clean and tight.
- Ignition OFF. Verify that there is 0 volts present at the underhood fuse block stud 1 terminal X7-1.
- If there is voltage present at stud 1, test the auxiliary battery relay and the run relay for a stuck closed condition. If OK, test the auxiliary battery positive cable for a short to voltage.
- Start the engine. Verify that there is greater than 12 volts present at the underhood fuse block stud 1 terminal X7-1.
- If less than the specified value, test the following components for an open/high resistance:
- SEO B1 fuse
- 125 A MEGA fuse
- Fusible link 2
- Fusible link 3
- Auxiliary battery relay
- Run relay
- If less than the specified value, test the following components for an open/high resistance:
- Reconnect the auxiliary battery.
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.