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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 616 (DATA LINK COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U1001-U1254: MODULE COMMUNICATIONTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 1. A module which loses power supply during an ignition cycle will cause other modules to set Lost Communication DTCs.
- 2. A module which loses ground during an ignition cycle will cause other modules to set Lost Communication DTCs.
- 3. The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
- 7. The module which was not communicating may have set Lost Communication DTCs for those modules that it was monitoring.
- 9. The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules in order to avoid future misdiagnosis.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.