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.

2008 Hummer H3 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Installation procedure

WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: View Of OnStar® Module

Courtesy of GENERAL MOTORS CORP.

When replacing the VCIM, record the 11-digit electronic serial number (ESN) and the 10-digit station identification (STID) number from the label on the new VCIM.
Reconnect the electrical connectors the module.

Fig 2: View Of Communication Interface Module

Courtesy of GENERAL MOTORS CORP.

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.