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The brake pedal position (BPP) sensor is used to sense the action of the driver application of the brake pedal. The BPP sensor provides an analogue voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5 V reference voltage to the BPP sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the left and right brake lamp control circuits as well as the centre high mounted brake lamp control circuit illuminating the left and right brake lamps and the centre high mounted brake lamp.


Flashing brake lights would be super annoying but since all the brake lights on the Gen1 are LED this shouldn't necessarily shorten their life.

All 3 LED brake lights are fed from 3 individual voltage outputs of the K9 BCM which terminate to:

Pin 1 (brown/yellow) of the center brake LED connector
Pin 2 (light blue/grey) of the left brake LED connector
Pin 2 (white) of the right brake LED connector

So this mean U would need to wire all 3 brake LEDs together somehow in order to be able to control with this device unless you just only want 1 LED to flash such as the center brake LED!;)


Not sure if flashing brake lights would have helped the folks involved in the multiple crashes in the video above during clear/dry conditions at night...
 

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Discussion Starter #4
Thank you for your help. Would those pins/wires also control the signal on each side? The interesting part about this gadget is the 3-axis accelerometer and thought it might work somehow when driving in L.

If the signal is on the same wires as the brake than that won't work.
 

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Thank you for your help. Would those pins/wires also control the signal on each side? The interesting part about this gadget is the 3-axis accelerometer and thought it might work somehow when driving in L.

If the signal is on the same wires as the brake than that won't work.
It will if you use diodes. I think your best bet is a basic flasher system for the 3rd brake light.
 

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Some intel from the web on this:

1 Yellow/Brown Left Rear Turn Signal Lamp Supply Voltage
2 Light-Blue/Gray Left Tail Lamp Supply Voltage
3 White/Violet Rear Turn Lamp Feedback Signal
4 Black Ground
5–6 Not Used

1 Light-Green/Violet Right Rear Turn Signal Lamp Supply Voltage
2 White Right Tail Lamp Supply Voltage
3 White/Black Right Rear Turn Lamp Feedback Signal
4 Black Ground
5–6 Not Used

Exterior Lighting Systems Description and Operation

Park, Tail and License Lamps

The park lamps, tail lamps and license plate lights are turned ON when the headlamp switch is placed in the PARK LIGHT or LOW BEAM position or anytime the headlights are requested. When the BCM receives a request from the headlamp switch to turn ON the park lamps the BCM a sends out a PWM signal, which illuminates the park lamps, tail lamps and license plate lights.

Stop Lamps

The brake pedal position (BPP) sensor is used to sense the action of the driver application of the brake pedal. The BPP sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the BPP sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the left and right stop lamp control circuits as well as the center high mounted stop lamp control circuit illuminating the left and right stop lamps and the center high mounted stop lamp.

Turn Signal Lamps

Ground is applied at all times to the turn signal/multi-function switch. The turn signal lamps may only be activated with the vehicle ON/OFF switch in the Service Mode or ON position. When the turn signal/multi-function switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the BCM through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through their respective voltage supply circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF.
Found on this site: http://www.justanswer.com/chevy/8xu6v-chevrolet-volt-i-m-looking-tail-lights-wiring-schematic.html#

Brake and turn signal is the same wire.

Why does BCM require a rear turn lamp feedback signal? Found on a GM Diesel forum:

2007+ GM trucks and 2008+ GM vans use the BCM to flash the turn signals instead of a flasher relay. The BCM checks for burned-out turn signal bulcs by measuring the load, and uses a "fast flash" to notify the driver that a turn signal is burnt out. GM (and presumably every other manufacturer) had to do this because of this government mandate:

"A standard production vehicle will have BCM software that checks for two bulbs functioning in each rear turn signal bulb circuit. If one or more bulbs are inoperative, the BCM will “fast flash” the Instrument Panel Cluster (IPC) turn signal indicator as required by Federal Motor Vehicle Safety Standard (FMVSS) 108 and Canada Motor Vehicle Safety Standard (CMVSS) 108." (from GM Upfitter BULLETIN # 81)
 

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Discussion Starter #7
It will if you use diodes. I think your best bet is a basic flasher system for the 3rd brake light.
How would you go about wiring it with diodes to make all three lamps work with the flasher? If I'm thinking what you're thinking is get power from third light and run wires with diodes to brake lights and tap there?

Good info there Mister Dave. thank you.
 

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How would you go about wiring it with diodes to make all three lamps work with the flasher? If I'm thinking what you're thinking is get power from third light and run wires with diodes to brake lights and tap there?

Good info there Mister Dave. thank you.
Basically, diodes stop backfeeding through the signal. I would still avoid all 3 flashing as I'd bet your local laws prohibit flashing red lights of any sort.
 

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Discussion Starter #9
Probably, and makes for a quick install too...So, I am not able to find a diagram or color code for the rear third brake light to possibly access it from the driver side outer panel.
 

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Discussion Starter #10
Also the problem with the dioes now that I think about it is if you get power from the third light to power both brake lights with the dioed in the run to each would probably not work when signaling and the brakes are applied the same time, or am I thinking wrong?
 

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Discussion Starter #11
The cool part about this particular flasher is that it's programmable in so many ways and has the accelerometer built in, it would have been nice to have the lights even flashing once then steady while slowing down in L. Verry cool and only wish it had an app for it.
 

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Probably, and makes for a quick install too...So, I am not able to find a diagram or color code for the rear third brake light to possibly access it from the driver side outer panel.
You're looking for a brown/yellow wire. The schematic shows it on connectors X225, X900 and X905. X900 and X905 are shown in the liftgate area under the headliner/trim panels. I don't know where X225 is - perhaps on the K9 BCM.
 
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