Cruise control operation on 1.8 Valvematic 6 speed manual

[Konrad C]

I have to disengage the cruise control manually, before change gears. If the cruise control is not turned off, pressing the clutch to change gears, will cause the engine wildly. Is this normal operation or the engine should drop revs? 

[Berengaria]

Konrad C, what you have described is normal, but not advisable to do.

By definition, cruise control means that the car should be in perpetual motion in a high gear on open road. When in motion, the cruise control electronics do the work of keeping the car at a set speed irrespective of gradient. However, the only other thing keeping it moving is the engagement of the clutch to the drivetrain, and the stresses between the two as the engine nails the car along.

By dipping the clutch whilst in drive, it is like dipping the clutch whilst driving the car with your foot on the accelerator pedal - thinks what causes the momentary revving as the drive union is disturbed. The sensor activation when you dip the clutch to knock out the cruise control will always lag slightly. However it's the force of the clutch against the weight of driving the car along that, when the flywheel is disengaged is relieved of the stress against it, but with the same throttle driving force . This is why it revs.

Always tap the brake to emergency disengage cruise control, or switch it off / finger the stalk towards you.

[Konrad C]

31 minutes ago, Berengaria said:

Konrad C, what you have described is normal, but not advisable to do.

By definition, cruise control means that the car should be in perpetual motion in a high gear on open road. When in motion, the cruise control electronics do the work of keeping the car at a set speed irrespective of gradient. However, the only other thing keeping it moving is the engagement of the clutch to the drivetrain, and the stresses between the two as the engine nails the car along.

By dipping the clutch whilst in drive, it is like dipping the clutch whilst driving the car with your foot on the accelerator pedal - thinks what causes the momentary revving as the drive union is disturbed. The sensor activation when you dip the clutch to knock out the cruise control will always lag slightly. However it's the force of the clutch against the weight of driving the car along that, when the flywheel is disengaged is relieved of the stress against it, but with the same throttle driving force . This is why it revs.

Always tap the brake to emergency disengage cruise control, or switch it off / finger the stalk towards you.

Thank you jack. The reason why I mentioned this, was my brother says that the cruise control should lower the engine speed when the clutch pedal is pressed. He has a Renault Grand Scenic. I don't think Toyota is set up that way. I do press either the brake pedal or the cancel button on the cruise control. On hilly motorways like the A/M23, the shift indicator suggests to drop out of sixth gear (downshift). I have to cancel cruise before changing gear. It is good to know.