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 MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 170 (BODY CONTROL MODULES)REMOVAL & INSTALLATIONONSTAR® MODULES (VCU, VIU & VCIM)INSTALLATION (VCU)
1999 GMC Forward Control 5.7 R, Automatic
Installation (VCU)
1999 GMC Forward Control 5.7 R, AutomaticSECTION Installation (VCU)
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.
- Record 11-digit ESN from label on new VCU module.
- Install OnStar® VCU into module bracket assembly. Connect harness connector. Connect cellular coaxial cable to VCU until fully seated. Ensure locking tab (1) is secured to VCU.
- Install TRUNK TRIM PANELS.
- OnStar® system must be reconfigured. Press and hold white dot button until OnStar® status LED turns from Green to Red, and back again to Green. Connect a scan tool to DLC. Use ID INFORMATION menu to access new ESN.
- Move vehicle to an open area away from tall buildings, with a clear view of unobstructed sky. Allow vehicle to run for 10 minutes.
- Press blue OnStar® button to connect to OnStar® call center. Tell advisor vehicle has received a new VCU. Ask advisor to update customer account with new ESN. Follow any additional instructions from OnStar® advisor. Ask advisor to activate OnStar® personal calling feature, if available.
RENDER: 1.0x
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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.