Cruise Control Quirk

[oldscsc]

Got a quick question for ya'll. I use my cruise quite a bit, even sometimes in the city. The cruise works fine, and I cancel it by tapping the brake. I noticed when I got the car and never asked...when I tap the brake, it revs up. It probably jumps ~ 500 RPM when it does it. I'll try to get a video today. I can barely, barely (not even enough to activate the brake lights I don't think) tap the brake and it will rev up and stay there. It doesn't accelerate, just revs up. I would think it's coming out of overdrive but it does the same thing in town. Ideas?

[Olds W31]

If you are accelerating, and tap the brake to release the cruise, your torque converter may/will unlock, causing the engine to rev but the car not to speed up...You can try this without the cruise...just maintain a steady speed over 50 (lock up is usually 42-45mph, but we are talking about GM)...keep your foot on the gas, tap the brakes with your left foot (enough to turn the lights on, not enough to brake the car)....you should see the tach rise as the converter unlocks...

[oldscsc]

42 MPH...it will do it at lower speeds than that, but I'll try that on the way home if I remember. Why wouldn't this happen in any other vehicle I've driven? The truck, the Suburban, nothing I've driven has done this, just wondering...

[95 vert]

I'm gonna say maybe a vacuum leak? Weak brake booster?

[Andrew]

its normal. really. its a 1st gen thing.

[AL]

Perfectly normal. Mine does it to.

[GP1138]

It's a good way to test to see if your TCC is engaging. My 4-door GP and Z34 never did this, their TCC's were faulty. My current car does. Normal.

[oldscsc]

I checked on the way home yesterday and it does unlock without the cruise on. Thanks all.