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.
System Components
Powertrain Control Module (PCM)
The Powertrain control module monitors the inputs from various modules on the serial data to determine the final top speed limiting value by selecting the lowest requested top speed limit.
Body Control Module (BCM)
The body control module monitors the top speed limiting requests from serial data communication modules (listed below) along with internally set values (tire, propshaft, valet, and teen limits) to determine the lowest top speed limit and transmits the value to engine control module for final top speed limit determination.
Electronic Brake Control Module (EBCM)
The electronic brake control module (EBCM) monitors the brake system to determine if a speed limiting signal should be sent to the BCM.
Suspension and Damping System
The suspension and damping system monitors the active suspension to determine if a speed limiting signal should be sent to the BCM.
OnStar Enhanced Services
The OnStar Module communicates with OnStar to determine if a speed limiting signal should be sent to the PCM.
Automatic Leveling Control
The automatic leveling control monitors the leveling system to determine if a speed limiting signal should be sent to the BCM.
Integrated Chassis Control Module
The integrated chassis control module monitors chassis controls to determine if a speed limiting signal should be sent to the BCM.
Rear Driveline Control Module / Transfer Case Control Module
The rear driveline control module / transfer case control module monitors the rear driveline or transfer case to determine if a speed limiting signal should be sent to the BCM.
Hybrid Module
The hybrid module monitors the hybrid system to determine if a speed limiting signal should be sent to the PCM.
Driver Information Center
The driver information center alerts the driver when the top vehicle speed is being limited.
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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.