LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2016 >> XTS Base >> Repair and Diagnosis >> Body & Frame >> Door Locks >> Keyless Entry System And Remote Functions >> Description and Operation >> Keyless Entry System Description and Operation >> Notes
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Keyless Entry System Description and Operation: Notes

Fig 1: PEPS Standard Block Diagram
GM3269816Courtesy of GENERAL MOTORS COMPANY
Callout Component Name
B27RR B27RR Door Handle Switch - Right Rear Exterior
B27LR B27LR Door Handle Switch - Left Rear Exterior
B27P B27P Door Handle Switch - Passenger Exterior
B27D B27D Door Handle Switch - Driver Exterior
S58A S58A Rear Compartment Lid Unlatch Switch - Exterior
K84 K84 Keyless Entry Control Module
K9 K9 Body Control Module
T10G T10G Keyless Entry Antenna - Rear Fascia
T10E T10E Keyless Entry Antenna - Rear Compartment
T10N T10N Keyless Entry Antenna - Passenger Door Handle
T10K T10K Keyless Entry Antenna - Center Console Rear
T10M T10M Keyless Entry Antenna - Driver Door Handle
T10J T10J Keyless Entry Antenna - Center Console Front
K77 K77 Remote Control Door Lock Receiver

Keyless Entry System Description and Operation - Active 

The keyless entry system is a vehicle entry device. The keyless entry system is used in conjunction with the door locks to unlock the vehicle. Keyless entry will lock/unlock a door or open the rear compartment lid when a corresponding button on the keyless entry transmitter is pressed. This is accomplished by the transmitter sending a radio frequency to the remote control door lock receiver antenna that has a direct link to the body control module (BCM). The BCM interprets the signal and activates the requested function or requests the appropriate ECU to activate the function via a serial data message. A low transmitter battery or radio frequency interference from aftermarket devices, such as 2-way radios, power inverters, computers, 12 V power outlet USB adapters, etc., may cause a system malfunction. High radio frequency traffic areas, such as gas stations that use pay-at-the-pump radio frequency transponders, may also cause interference that could lead to a malfunction. Keyless entry allows you to operate the following features:

Keyless Entry System Description and Operation - Passive 

Passive keyless entry allows entry to a locked vehicle without pressing any buttons on the keyless entry transmitter. You must only have the transmitter with you. The passive entry system use low frequency antennas in several different areas on the vehicle to determine the location of the transmitter. When passively opening a locked door or the rear compartment, you must have a programmed transmitter with you in your pocket, purse, or briefcase within a one meter range.

When an exterior door handle button is pressed or the rear compartment touch pad is pressed, the BCM sends a serial data message to the keyless entry control module directing the keyless entry control module to send a low frequency challenge from the keyless entry antenna to the keyless entry transmitter. Because of the low frequency, communication range is limited. The antenna will emit the challenge in a one meter range. The transmitter must be within this range to receive the challenge. The transmitter receives this challenge and emits it's response as an RF message, which is received by the remote control door lock receiver. If the response is correct, entry into the vehicle will be allowed.

As a customer convenience feature, the keyless entry system will notify the driver if the transmitter has been left in the vehicle after exiting by chirping the vehicle horn three times. This may be turned off using vehicle personalization. Also, if the transmitter is left in the vehicle after the central door lock switch has been used to lock the vehicle, the driver door will remain unlocked after exiting the vehicle. This is intended to prevent locking the transmitter in the vehicle and being unable to access it.

Keyless Entry System Description and Operation - Keyless Start 

The keyless start portion of the keyless entry system allows vehicle starting, having only the transmitter as your key. The keyless start system uses low frequency antennas in three different locations on the vehicle to determine the location of the transmitter. Multiple antennas are used to ensure complete coverage of the vehicle interior and rear compartment. When using the keyless start system, a programmed transmitter must be in the vehicle's interior, in the driver's pocket, purse, or briefcase.

When the ignition mode switch is pressed, the low frequency antennas emit a challenge to the keyless entry transmitter. The transmitter receives this challenge and emits it's response as an RF message, which is received by the remote control door lock receiver. If the response is correct, vehicle starting will be allowed. If RF communication is interrupted, a "No Remote Detected" message will be displayed on the driver information center. In these cases, the transmitter can be placed in the transmitter pocket located in the center console, under the cupholder. The immobilizer antenna coil is located directly beneath the transmitter pocket. Placing the transmitter in the pocket will create a low powered coupling between the transmitter and immobilizer antenna, allowing communications to occur and enabling vehicle starting.

The keyless entry system has the following components: