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.
2003 Cadillac CTS AutomaticFACTORY OEM SERVICE PROCEDURE
Data Link Communication DTCS
DATA LINK COMMUNICATION DIAGNOSTIC TROUBLE CODE (DTC) LIST
| DTC | Description |
|---|---|
| DTC U1000 and U1255 | Node Alive Message Has Not Been Received From Unidentified Module |
| DTC U1001 to U1254 | Module U1XXX Communication |
| DTC U1300, U1301, or U1305 | No Valid Messages Are Detected On The Class 2 Serial Data Circuit |
| DTC U2100 | CAN Circuits |
| DTC U2102 | ECM Is Not Calibrated To The Vehicle |
| DTC U2104 | CAN Circuits |
| DTC U2106 | CAN Circuits |
Factory Service Tools
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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.