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 MANUALSCHEVROLET1999CORVETTE 2D COUPE, STANDARDREPAIR AND DIAGNOSISBODY & FRAMEBODY, CAB CONTROL SYSTEMSBODY CONTROL MODULESDIAGNOSTIC TESTSDTC U1255: SERIAL DATA LINE MALFUNCTIONTESTING
1999 Chevrolet Corvette 2D Coupe, Standard
DTC U1255: Serial Data Line Malfunction: Testing
1999 Chevrolet Corvette 2D Coupe, StandardSECTION Testing
- Perform DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK under SYSTEM TESTS. Go to next step.
- Turn ignition off. Install scan tool. Turn ignition on. Using scan tool, attempt to establish communication with other systems connected to data line (i.e., PCM, IPC, RFA). If scan tool communicates with other systems, go to next step. If scan tool does not communicate with other systems, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK under SYSTEM TESTS.
- Check serial data line for following intermittent conditions:
- Short to ground.
- Short to voltage.
- Check star connector No. 1 (ensure bus bar is properly inserted).
- Loose or damaged terminals.
If no problem is found, go to next step. If problem is found, repair as necessary. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. After repairs, go to step 6 .
- Turn ignition off. Reinstall all components and connectors. Turn ignition on. Clear DTCs. Check for DTCs. If DTC U1255 is current, go to next step. If DTC U1255 is not current, system is operating properly.
- Replace BCM and program. See BODY CONTROL MODULE (BCM) under REMOVAL & INSTALLATION. See BCM PROGRAMMING/RPO CONFIGURATION under PROGRAMMING. After repairs, go to next step.
- Turn ignition off. Reinstall all components and connectors. Turn ignition on. Clear DTCs. Perform DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK under SYSTEM TESTS.
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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.