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 1596 (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 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Using the DTC Descriptor and Diagnostic Aids, determine the module that is not communicating. Utilize the schematics to identify if there are any other modules between the module that sets the DTC and the module that is not communicating.
- Ignition OFF, disconnect the harness connector at the module that is not communicating.
- Test for less than 10 ohms between the module ground circuits and ground.
- If greater than the specified range, test the ground circuit for open/high resistance.
- Ignition ON, verify that a test lamp illuminates between all battery positive voltage circuits, including wakeup and enable circuits, and ground.
- If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, test or replace the module.
- Verify that a test lamp illuminates between all ignition voltage circuits and ground.
- If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, test or replace the module.
- Ignition OFF, test for less than 1 ohm on the high speed GMLAN serial data circuits between the non-communicating module and the module that set the DTC.
- If greater than the specified range, test the serial data circuits for an open/high resistance. If all circuits test normal, replace any module that is located between the module that sets the DTC and the non-communicating module.
- If all circuits test normal, test or replace the module that is not communicating.
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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.