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2014 XTS V-Sport Platinum
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2,230 Posts
Discussion Starter · #1 ·
I was wondering if the ACC lights the brake lights when it is slowing the car down?
 

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2006 STS 1SG & 2007 STS 1SE
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14 Posts
I once saw a Caddy with the brakes lights flashing quickly. I wonder just what they do.

The thought had crossed my mind to have someone follow me & check my car while on ACC under braking. I never have done it.
 

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'05 STS4
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668 Posts
I've always assumed they'd just have to. I mean, if someone pulls in front of me the ACC applies the brake hard enough for the "nose" to go down,,,, I can't imagine the brake lights Not coming on at that point.

I guess the answer would be in a wiring diagram to see if the ECM, Cruise, or ACC modules have any connection to the brake lights.......
 

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2014 XTS V-Sport Platinum
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2,230 Posts
Discussion Starter · #7 ·
Found the answer...

DISTANCE SENSING CRUISE CONTROL (DSCC) MODULE
The DSCC module contains the forward looking sensor (FLS) radar and the DSCC controller. The DSCC module utilizes the FLS radar to identify and classify objects in the road environment. The FLS radar scans the road environment to detect targets within its specified field of view. The DSCC controller then makes throttle and/or brake commands to the engine control module (ECM) and electronic brake control module (EBCM) via the GMLAN serial data circuit in order to control the vehicle acceleration/deceleration based on the data from the FLS radar. The ECM and EBCM provide throttle control and automatic braking needed for proper cruise speed adjustment. An internal yaw rate sensor is used by the DSCC module to determine the predicted path of the ACC vehicle. The main power feed for the DSCC module is the battery and this signal is always at battery potential. However, the ACC System only activates when the ignition 1 input is active and in the RUN position. The ignition 1 voltage signal to the DSCC module has to be 9.2 volts or more to be considered active by the DSCC module. When the ignition 1 signal is not active, all ACC functions are disabled. The following is a list of the DSCC module functions:

* The FLS radar processes the road environment to get data concerning any vehicle ahead of the ACC vehicle. Detection, parameter estimation, tracking, object classification and diagnostics are the primary FLS radar functions. When an object is detected, the DSCC controller calculates the object range, range rate, acceleration and azimuth angle parameters.
* The DSCC module performs ACC state processing automatically-distance control or speed control. The ACC System operates in 2 possible states-Cruise or Follow. The normal operating state is Cruise, whereby the vehicle speed is controlled to match the driver selected set speed. When a preceding forward target is identified by the FLS radar, the ACC System will automatically transition into the follow speed state to provide proper lane spacing behind the target vehicle in front. The preceding vehicle's speed and acceleration, with the ACC vehicle speed, acceleration and distance between the two vehicles will be used to determine the ACC follow speed limit. The ACC follow speed limit will ensure that an acceptable distance is maintained to the preceding vehicle.
* The DSCC module determines the follow speed limit for throttle control by the ECM.
* The DSCC module arbitrates the ACC System brake and throttle control between the EBCM and the ECM.
* The DSCC module requests brake light activation during automatic braking.
* The DSCC module provides operational feedback to the vehicle driver. The DSCC module sends signals for telltales and messages to be displayed on the head-up display (HUD) or driver information center (DIC) via the IPM. The DSCC module will provide audible feedback to the driver via the IPM and the radio amplifier as well.
 
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