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 MANUALSCHEVROLET2006SUBURBAN K2500, 6.0 UREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1435 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U1862CIRCUIT/SYSTEM TESTING
2006 Chevrolet Suburban K2500, 6.0 U
Circuit/System Testing
2006 Chevrolet Suburban K2500, 6.0 USECTION Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector X2 at the SDG module.
- Ignition OFF and the scan tool disconnected, open and close the driver door, and wait 1 minute.
- Test for less than 5.0 ohms between the ground circuit terminal 18 X2 and ground.
- If greater than the specified range, test the circuit for an open/high resistance.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 8 X2 and ground.
- If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance.
- Test for 10.5-12.5 volts between the serial data communication enable circuit terminal 16 X2 and ground.
- If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the applicable communication/control module.
- Ignition OFF, connect the harness connector X2 to the SDG module.
- Ignition OFF, disconnect the harness connector X1 at the SDG module.
- Ignition ON, test for 2.1-2.5 volts between the high speed GMLAN serial data bus low circuit terminal listed below and ground:
- Terminal 15 X1
- Terminal 16 X1
- If greater than the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the applicable communication/control module.
- If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the applicable communication/control module.
- If all circuits test normal, replace the SDG module.
IMPORTANT:
The scan tool must be disconnected and the ignition switch OFF for 30 seconds for proper test results.
RENDER: 1.0x
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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.