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[Terbs]

You all know my affliction with cruise control....but how does it work

Also, how does it slow the car down...does it use the brakes, as after I got cruise control on, I noticed the brake light in the rear window did not light up when we went downhill.

Just curious

[the alarming man]

the old control on the discovery used a vacuum system on the accelerator...not sure about omegas but I am guessing to slow the car down it uses engine braking

[Steve B]

You all know my affliction with cruise control....but how does it work

Also, how does it slow the car down...does it use the brakes, as after I got cruise control on, I noticed the brake light in the rear window did not light up when we went downhill.

Just curious

Thats dangerous  You need to turn around and face the front   

[05omegav6]

On DBW cars, it's controlled by the engine ecu. Autos might have some (very limited) gearbox input as well.

On cabled throttles, the actuator has a second cable attached to the throttle. As an experiment... on an open stretch of motorway accelerate to 70 and set the cruise control. Brake down to about 55 and feather your right foot so that it just touches the accelerator pedal then press resume. You should feel the pedal pull away from your foot a fraction...

If in sports mode, the slushbox should kickdown to resume the set speed. Braking is entirely engine braking not road wheels, so selecting a lower gear as required still applies. Equally if the car starts to run away down hill cruise switches off, I believe at +/- 10%

[Terbs]

Thanks for that explanation Al...appreciated.
What made me think about the braking, was when on the M3 heading north, you probably are familiar with the downhill stretch prior to the A33 Reading exit, we were popping along at 70ish when we started on that incline. The car seemed to pick up speed, then it really slowed fast, but (looking in the mirror  ) I saw no brakelight reflection, then was away again as we got just under 70mph. Seemed to control it well after that. Was just a bit unnerving as it initially went for it down that hill.

[steve6367]

Both mine drop a gear if running away done hill - they do that cruise on or off though.

Steve

[TheBoy]

Absolutely no braking on Omega cruise controls.

[YZ250]

This is something that I have to keep an eye on with using two cars. The Omega tends to roll on a bit down hill on cruise, enough to get you a ticket in a 30mph zone, but my other car is true to within a couple of miles per hour, so you can rely on it to hold the speed downhill. 

[05omegav6]

This is something that I have to keep an eye on with using two cars. The Omega tends to roll on a bit down hill on cruise, enough to get you a ticket in a 30mph zone, but my other car is true to within a couple of miles per hour, so you can rely on it to hold the speed downhill. 

The latest cars use the Esp/autobrake system to fine tune vehicle speed. The cruise set up on the Merc was very impressive in this regard