The short answer is the handle has capacitive membrane for unlock. But here is the complete description from the factory manual. The membrane is why the lights flash when you wash with the key in your pocket.
DESCRIPTION - PASSIVE ENTRY
A Passive Entry Keyless Go (PEKG) system is available factory-installed equipment for this vehicle. The PEKG system allows the vehicle to be unlocked without the use of a mechanical key, as long as an authorized FOB with Integrated Key (FOBIK) is in the possession of the individual or in close proximity to the aperture of the vehicle that is to be unlocked. All other features and Customer Programmable feature settings of the power lock system and the Remote Keyless Entry (RKE) system function the same as they would on vehicles without the PEKG system option.
The PE system includes the following major components, which are described in further detail elsewhere in this service information:
Door Handle Switches - Each PE door outside handle (also known as a Smart handle) is equipped with three switches and an Integrated Circuit (IC). A tactile Lock switch is located on the outer horizontal surface of each door handle pull, a capacitive Unlock switch membrane is located on the inner vertical surface of the handle pull, while a Hall effect switch and an IC are concealed within the handle pull unit.
Low Frequency Antennas - Standard cab models have the LF antenna located in each front door. Quad, Crew, and Mega cab models have the LF antenna located in each rear door. All cab models include a LF antenna mounted beneath the front of the center floor console and one mounted to the rear cabin wall.
Radio Frequency Hub Module - The Radio Frequency Hub Module (RFHM) (also known as the RF Hub) is the Passive Entry Keyless Go (PEKG) system control module and RF receiver located on the rear cabin wall. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Radio Frequency (RF Hub) - Description).
Basic PE notes:
NOTE:
If wearing gloves on your hands, or if it has been raining on the Passive Entry door handle, the unlock sensitivity can be affected, resulting in a slower response time. This is a common complaint that is deemed normal operation at this time.
Passive entry can be turned on/off by navigating through the options of the U-Connect Touch Screen.
Certain functions and features of the power lock system rely upon resources shared with other electronic modules in the vehicle over the CAN data bus network. For proper diagnosis of these electronic modules or of the CAN data bus network, the use of a scan tool and the appropriate diagnostic information are required.
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