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 MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 72 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSCAN TOOL DOES NOT COMMUNICATE WITH GATEWAY ISOLATED HIGH SPEED GMLAN DEVICECIRCUIT/SYSTEM VERIFICATION
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol
Circuit/System Verification
2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Verification
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON/Vehicle In Service Mode.
- Verify that DTC U0073, U0074, U0075, U0077, U0078, U007A, P06E4, P1EB9, U1814, U2099, B1325, B1330, B1370, B1380, B1424, B1428, B1440, B1441, B1517, C0800, C0899, C12E1, P0560, or P0562 is not set.
- If any of the DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If none of the DTCs are set
- If any of the DTCs are set
- Attempt to communicate with all devices on the gateway isolated high speed GMLAN serial data circuits. Refer to Data Link References to determine which devices are on the gateway isolated high speed GMLAN bus.
- Verify which devices are communicating on the gateway isolated high speed GMLAN serial data circuits.
- If only one device is not communicating
Refer to Circuit/System Testing - Testing the Device Circuits.
- If one or more devices are communicating but not all, except the K56 Serial Data Gateway Module
Refer to Circuit/System Testing - Testing the Serial Data Circuit for an Open/High Resistance.
- Go to next step: If none of the devices are communicating, except the K56 Serial Data Gateway Module
- If only one device is not communicating
- Refer to Circuit/System Testing.
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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.