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 MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 246 (BODY CONTROL MODULES)DIAGNOSTIC TESTSDTC U1500: ONSTAR® (GENERATION F1) VEHICLE COMMUNICATION INTERFACE MODULE INTERNAL MALFUNCTIONTEST PROCEDURE
1998 Chevrolet Suburban K2500, 7.4 J, Part Time
Test Procedure
1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Test Procedure
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
- If cellular communication diagnostic system check has been performed, go to next step. If cellular communication diagnostic system check has not been performed, perform CELLULAR COMMUNICATION DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.
- Connect a scan tool to DLC. Retrieve DTCs from VCIM. If DTC U1500 is set as current, go to next step. If DTC U1500 is not current, see DIAGNOSTIC AIDS .
- Replace VCIM. See ONSTAR® MODULES under REMOVAL & INSTALLATION. Perform OnStar® setup procedure. See VEHICLE COMMUNICATION UNIT/VEHICLE INTERFACE UNIT (ONSTAR®) .
- Using scan tool, clear DTCs. Operate vehicle within code enable criteria. See CODE ENABLE CRITERIA . If DTC resets, repeat test beginning at step 1.
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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.