If one day your cruise control stops working, the problem may be due to something simple. So before you take the car to the dealer, you can do some checks yourself. Cruise control may stop working due to following components:
· Stop lights
· Brake light pedal switch
· Steering wheel cruise switch
· Cruise control module
First, check the stop lights. If both left and right stop lights are burnt out or not working, the cruise control will not work, even if the centre LED stop light still works. This was the situation in my case. The cruise dash light will turn on but you will not be able to get the car to hold any speed. If either left or right light still works, the cruise will also work. As mentioned below, replacing the stop lights with LED lights will also cause a problem with cruise control because LED lights do not have the same resistance as light bulbs. Also check the brake light fuse in the engine bay to make sure it is not blown, as this may also interfere with cruise control.
Next, check the brake light pedal switch. It can be disconnected and removed from the car and has four contacts. Two contacts control the brake lights and are normally open. They become closed and turn on the brake lights when the brake pedal is pressed. The other two contacts control the cruise and are normally closed but become open when the brake pedal is pressed. They disconnect cruise control when the pedal is pressed. All of the four contacts are important for cruise control operation, and the switch can be checked for proper operation with a multimeter or test lamp. The switch can also be easily adjusted in relation to how it is positioned to the brake pedal.
If stop lights and brake pedal switch are ok, the problem may be in the steering wheel cruise switch. The switch is electronic and I could not test it with a multimeter but it can be removed and replaced with a new one. This, however, will require the removal of steering wheel. It is not hard and there are videos on the internet on how to do it. It will require an allen key (8mm I believe) and will also require disconnecting the air bag and cruise control wiring to the steering. Be carefull as the steering wheel contains an airbag, so make sure you disconnect the air bag wiring to the steering.
If the above did not fix your problem, check the fuse for cruise control to make sure it is not blown. If the fuse is ok, then the cruise module module may be faulty. I believe it is located near the front end of transmission below the fan and aircon switches and could be replaced.