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.
Telephone/Telematics Control Module J526 , replacing and reconfiguring: Notes
After replacing the Telephone/Telematic Control Module, the OnStar system needs to be reconfigured and the Telematics Service Mode deactivated using the Vehicle Diagnostic Testing and Information System VAS 5051.
Have the VIN and customer details on hand.
- DO NOT exchange Telephone/Telematic Control Modules between vehicles! Each module contains specific Station Identification (STID) and Electronic Serial Number (ESN) data unique to the VIN. This data is used by OnStar and National Cellular Telephone Network to identify the vehicle and administer the customers account.
- Failure to reconfigure the control module after replacement will prevent OnStar services and features from functioning, and will result in a customer return for repair.
- Always replace the emergency (back-up) battery when replacing the Telephone/Telematic Control Module.
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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.