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 MANUALSSATURN2000LW2 AUTOMATICREPAIR AND DIAGNOSISBODY & FRAMEBODY, CAB CONTROL SYSTEMSBODY CONTROL MODULESDIAGNOSTIC TESTSDTC U1301: CLASS-2 SERIAL DATA LINK HIGH
2000 Saturn LW2 Automatic
DTC U1301: Class-2 Serial Data Link High
2000 Saturn LW2 AutomaticSECTION DTC U1301: Class-2 Serial Data Link High
NOTE:
Sensing and Diagnostic Module (SDM) sets DTC U1300 for a short to ground or short to voltage on class-2 serial data link. If class-2 serial data link is shorted to voltage, SDM will set DTC U1300 and BCM will set DTC U1301.
- Perform VEHICLE ON-BOARD DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. If vehicle on-board diagnostic system check has been performed, attempt to establish communication with BCM, PCM or SDM. If communication can be established with BCM, PCM or SDM, class-2 serial data link is not shorted at this time. Go to next step.
- To aid in diagnosing an intermittent, turn ignition on. Using scan tool, select DIAGNOSTIC CIRCUIT CHECK- - -CLASS 2 MESSAGE MONITOR and monitor any modules on class-2 serial data link. If INACTIVE is displayed on all modules, class-2 serial data link is currently shorted to voltage. Check for intermittent short to voltage in Purple wire between BCM and all other modules on class-2 serial data link. See WIRING DIAGRAMS . Controller name will not be displayed until ignition is on and scan tool receives correct module ID over class-2 serial data link. Repair as necessary and retest operation.
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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.