Brake service light comes on while cruise control activated

[tgams]

went on a trip today, and while cruising down the interstate about 75, the service brake light came on. If I de-activate the cruise control it goes away.. any idea why? Brakes seem to work perfectly, not down on fluid. Never came on before at all. 2010 expy xlt, 120000 miles

 

[bobmbx]

I'm gonna date myself here....nobody laugh, got it?

Does your cruise control use the vacuum system? If so, a leak in the vacuum tubing to the CC controller/actuator can affect the vacuum booster, causing the brake service light to activate.

At least, in the old days that could happen.

 

[Trainmaster]

Yeah, you dated yourself there. It's all electronic now with a motor controlling the throttle plate.

 

[tgams]

I thought about a vacuum leak, looked at all the hoses and stuff around the brake booster /master cylinder it’s the strangest thing, thinking it might be in the speed sensor or a relay problem, but I guess I need a decent schematic....

 

[Plati]

Yeah, you dated yourself there. It's all electronic now with a motor controlling the throttle plate.

I thought on newer vehicles .. brakes were also used in cruise control & traction control, etc?

 

[Michael Shepherd]

Adaptive cruise requires the brakes in order to maintain following gap/distance.

 

[tgams]

Does this truck brake automatically in cruise?

 

[mquick5]

Adaptive cruise requires the brakes in order to maintain following gap/distance.

I didn't think the 3rd gen had adaptive cruise? My 17 either dont have it or it dont work, idk.

Sent from my SM-G930T using Tapatalk

 

[tgams]

does anyone else have any ideas? On the way home Thursday I tried it again, activated cruise control...came on and maintained speed fine...after about five minutes in cruise, the service brake system light came on and the message center indicated service brakes..I turned cruise off, and about 30 seconds afterward the light went off, and the message went away. This happened twice in a row, then i just left cruise off and the indication never came back. When I got home i scanned the computer for codes and found none.

 

[tgams]

anybody?