Do the brake lights come on when ACC activates them?

[olyeller]

When adaptive Cruise Control kicks in and drastically slows the car, do the brake lights activate? I’d assume they would but have no way to check.

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[Trigganometry]

Pretty sure crash protection kicks on your 4 way flashers. Not sure about cruse control and brakes though

 

[towpro]

I think they do because the Trailer brake controller needs to wire into the High mount center stop light as an input so it knows when to apply the brakes on the trailer, but that is my educated guess.

 

[NOVA_Ranger]

I’d have to go out on a limb and say yes, only because my rear bumper is intact.

 

[olyeller]

Can’t imagine they don’t but my old school knowledge has the brake light switch on the brake pedal. I’d think they’d be computer controlled now but I’d like to know for sure. The other day I had some brain dead person cut in front of me very closely. The ACC activated the brakes to avoid a collision. I worried about the guy who was tailgating me and if he got the brake light warning.

 

[olyeller]

To be clear, I’m asking about ACC. Although, now you have me curious about PCA as well

 

[DT444T]

I think they do because the Trailer brake controller needs to wire into the High mount center stop light as an input so it knows when to apply the brakes on the trailer, but that is my educated guess.

Why couldn't we just get brake signal from the regular brake lights, then? For some reason it HAS to be the third brake light.

 

[Danager]

Why couldn't we just get brake signal from the regular brake lights, then? For some reason it HAS to be the third brake light.

It HAS to be the CHMSL because you actually have to interrupt at the plug - the additional TBC module has a male and female plug. You COULD go all the way back to a brake light and plug-in there, it would just be a lot more work. Not sure why the use of actual plugs. Somebody must have determined this was better/safer that a tap or soldering.

As for the original question - ACC activates the brake lights as it activates the brakes.

 

[olyeller]

so ACC....youre in behind a car on the interstate, cruising at 70mph. you have it set to the mid range.

the car in front slows slightly....your system reduces the throttle position to maintain the gap

a few miles down the road, the car brakes but moderately. your system would likely see the need to brake as well, as letting off the throttle wont be enough. but this braking is limited.

Another mile down the road, there's road debris and heavy traffic slowed considerably. your system would do these first two steps, and figure out the limited braking is insufficient and it would send you a warning chime and visuals. You now have to take over the brakes.

if you do not react fast enough, pre collision assist slaps the back of your head and takes over hitting the brakes at max force....but depending on a number of factors, it may be too late and your hitting the traffic ahead of you anyways, but hopefully at a lot less force.

All good info but when either system takes over and applies the brakes, does it also activate the rear brake lights to warn those behind you that you are slowing?

 

[JACKSMYDOG]

Less than a week after getting the truck I had my PCA kick in as I passed between a truck on my right and a traffic island on my left. My lane was clear so I was cruising at ~55 mph and PCA slammed the brakes pretty hard. If there was snow on the road, I am fairly certain I would have lost control and been into the island or truck. I turned it to warnings only, which still go off far too often.

ACC braking kicked in one day for a car in the next lane on a freeway because of the bend in the road. Not as dangerous, but not ideal either. I turn it off for multi-lane roads after that.

I still liked it for rural driving, but get too many blocked sensor warnings, which require turning it off in settings or not using cruise until you can clear the sensors. I got tired of that as well, so I turned it off completely.

Now I just get the "ACC is turned off warning" EVERY time I activate cruise.

 

[DT444T]

have to interrupt at the plug

Why?

Why can't we get signal coming from the source rather than at the load?

For info: I installed my TBC myself.

 

[Danager]

Why?

Why can't we get signal coming from the source rather than at the load?

For info: I installed my TBC myself.

Well, with my limited knowledge of engineering, the aftermarket world of installers, vehicle techs/mechanics, and liability…
I would say it is preferred to use a plug as it is the same mechanical connection as used by the manufacturer. Also, by connecting at the light, a failure of said connection only takes out the light. Connecting further upstream could affect all brake lights.

 

[Jason B]

Why?

Why can't we get signal coming from the source rather than at the load?

For info: I installed my TBC myself.

YOU can , but Ford won't allow techs to cut into wires for splicing.

 

[DT444T]

YOU can , but Ford won't allow techs to cut into wires for splicing.

So the big reason they send you after the CHMSL instead of the rear brake light is that it's closer to the location of the TBC.

 

[D Fresh]

Why?

Why can't we get signal coming from the source rather than at the load?

For info: I installed my TBC myself.

You can tap into signal at the module to avoid pulling all that trim.

But if you want to avoid tapping, you have to interrupt at the plug.

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