This bulletin from GM applies to all cars and trucks from 2014 and earlier.

Some customers may comment on poor or no transmitter range when using the remote keyless entry (RKE) and/or remote vehicle start (RVS).
In some cases, the range has been limited to a few feet.
Some aftermarket devices can cause frequency interference, which may affect the operating range of the RKE and/or RVS functions.

Inspect for any aftermarket devices installed or stored in the vehicle, such as cell phone or USB chargers plugged into an accessory port, wireless gate remotes, wireless winch remotes, etc.

Aftermarket devices like this USB inexpensive phone charger can interrupt the frequency and operating range of RKE and RSE functions.