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.
Brake Lock Differentials
Brake Lock Differentials (BLDs) are part of the ESP® base algorithm and tuned for on-road activity. Brake Lock differentials improve vehicle mobility by applying braking force to a driven wheel that is spinning faster than the mate on the same axle to provide an equal amount of torque for each wheel, thereby providing torque to the wheel with the most traction. The on-road BLD is calibrated for on-road conditions such as when one wheel is on ice or gravel and the other is on dry pavement, this type of condition is called a split-friction surface.
Vehicles equipped with the Off-Road Group (sales code AWL) include a separate set of BLD calibrations that are designed for Off-Road mode use while crawling over obstacles, during heavy articulation activity, split-friction surfaces and other conditions. Off-Road BLDs direct torque from the wheel that slips to the wheel with more grip on a given axle helping maintain forward mobility over all types of off-road terrain.
Off-Road BLD calibrations are activated when the vehicle is in the Off-Road mode. The Off-road calibration applies much more aggressive and longer duration brake caliper clamping than the calibration for on-road BLDs to achieve the desired performance over off-road events.
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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.