There may be a battery draw condition due false wake-up requests to the Body Control Module (BCM) on some 2022-2024 Tahoe, Suburban, Yukon and Escalade models equipped with the hands-free liftgate (RPO TC2).
The battery draw condition may be caused by an issue with the K171 Hands-Free Liftgate Sensor Control Module repeatedly sending a false wake-up request to the BCM commanding the liftgate to open. However, the power liftgate may or may not actually open unless specific operating conditions are present. For the power liftgate to open with the false hands-free request, the vehicle must be in Park, the power liftgate switch must be turned on, the hands-free setting must be enabled in the Vehicle Settings, and the key fob must be within 3 feet (1 meter) of the liftgate itself.
To determine if the Hands-Free Liftgate module (Fig. 11) is waking up the vehicle and causing the battery draw, remove the F35RA 10-amp fuse in the rear fuse block and check if the condition no longer occurs. With the fuse removed, the hands-free liftgate feature will not work, but the power liftgate will still function normally. Trailer Tire Pressure Monitor system (RPO UET) functions, if equipped, also will be lost while the fuse is pulled.
Fig. 11
There also may be a BCM software concern that is magnifying the battery draw if the BCM receives a wake-up request, which is more likely to occur when the vehicle is left unlocked and/or a key fob is left inside the vehicle. The BCM wake-up request doesn’t have to come from the Hands-Free Liftgate module to cause this issue, but it is the most common module that is waking up the BCM.
To reduce the battery draw magnification from the BCM, make sure the BCM has the latest programming updates.
In addition, advise owners not to leave the key fob(s) inside the vehicle and to lock the vehicle when not in use. Turning on the passive locking feature in the Vehicle Settings will ensure the vehicle is being locked when not in use.
If the concern includes the power liftgate opening on its own, or if the source of the vehicle waking up/battery draw is determined to be the K171 Hands-Free Liftgate Sensor Control Module, replace the module.
There is a new design Hands-Free Liftgate module that addresses the unwanted liftgate activation and potential battery drain. The new modules are stamped with a triangle. (Fig. 12) Vehicles built after October 2023 have the new design Hands-Free Liftgate module.
Fig. 12
Refer to Bulletin #24-NA-039 for more details.
Thanks to Mike Waszczenko
The triangle on control module part number 86777551 indicates the new design part in production. Part number 86777551 without the triangle should not be used or installed on the vehicle. The new control module part number 85038020 also has the updated internal components – without the triangle stamped on the module – and can be used.
We had some Hands-Free Liftgate modules with triangles and we’re getting new Hands-Free Liftgate modules with updated part numbers but no triangle. Are the newest module coming without the triangle?