* Transmission Problems: This is a high-probability cause. The grinding could indicate issues within the transmission, such as worn synchronizers, damaged gears, or low transmission fluid. Braking can exacerbate these problems by shifting weight and applying stress to the transmission components.
* Driveshaft/U-Joint Issues: A worn or damaged driveshaft or U-joint could be grinding when the brakes are applied. The braking force can cause the driveshaft to bind slightly, leading to the noise.
* Rear Differential Problems: Similar to the driveshaft, problems within the rear differential (worn gears, low fluid) can manifest as a grinding sound, especially under braking.
* Brake System Related (less likely): While less likely to be directly near the shifter, a brake caliper sticking or a problem with the parking brake mechanism could indirectly cause a grinding sound *near* the shifter if the vibration is transmitted through the chassis.
What to do:
1. Don't drive it further: Continuing to drive with this sound could cause significant and expensive damage.
2. Check the Transmission Fluid: Check the level and condition of your transmission fluid. Low fluid, dirty fluid, or burnt-smelling fluid are all strong indicators of transmission problems.
3. Professional Inspection: Take your Jeep to a qualified mechanic specializing in Jeep Grand Cherokees or to a reputable repair shop. Describe the sound and the conditions under which it occurs (braking). A proper diagnosis is crucial to avoid further damage and costly repairs.
Ignoring this problem could lead to a complete transmission failure or other serious drivetrain damage, resulting in a much more expensive repair. Get it checked out ASAP.
