What causes it to not engage in drive or reverse. Starts it fine and idles fine.

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! When your 2005 Chevy Trailblazer starts fine but won’t engage in drive or reverse, that sudden loss of acceleration at high speed could indicate an issue with the **transmission itself** or the **torque converter**. If the torque converter failed, it could prevent power from being transferred to the wheels, causing the engine to rev without moving the vehicle. However, given the high RPM revving you experienced, this could also be a sign of low or leaking **transmission fluid** or even an internal transmission failure. Check the fluid level and color—it should be a clear red, not dark or burnt. A professional diagnostic might be necessary to determine if it’s the torque converter, a transmission pump issue, or something more serious. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554.