Troubleshooting Your Car's Cruise Control

The cruise control mechanism found in today’s cars is designed to aid the driver in maintaining a stable cruising speed. Driving can be tiring especially during long road trips; that is why maintaining the integrity of the cruise control mechanism of your car is important. The cruise control works via an actuator mechanism, control module, and a speed sensor. As you activate your car’s cruise control, the speed sensor will send a signal to a control module and to the vacuum powered actuator that controls the accelerator. This means that while the cruise control system is active you can relax and take your foot off the accelerator. Deactivating your car’s cruise control is done by simply applying slight pressure to the brakes. Below are the materials and instructions you will need to troubleshoot problems with your car’s cruise control.

Step 1 - Check the Speed Sensor

cruise control wiring harness

Check the speed sensor wiring and look for signs of damage. Using a floor jack, lift the front portion of your car and locate the speed sensor. The speed sensor for your cruise control is normally located below the transmission and at the back of the engine. The speed sensor is like a small plug protruding off the transmission with various wires attached to it. Visually check the wires for any signs of damage. A faulty or damaged wire on your speed sensor means that the speed sensor cannot relay your vehicle’s speed.

Step 2 - Check the Fuse

two fuses showing a burnout

A power surge can easily blow out the fuse of your cruise control mechanism. The cruise control fuse is normally found in the fuse panel located below the steering wheel. Remove the cover of the fuse panel and locate the fuse for the cruise control using the fuse diagram on the fuse panel. Using a fuse puller, pull the fuse off the panel. Examine the cruise control fuse or use a fuse tester to determine if the thin metal strip inside the fuse is broken. If so, install a fresh fuse of the same amperage.

Step 3 - Check the Vacuum Lines

A cruise control mechanism has a vacuum-powered actuator connected to the control module by vacuum lines. Check for holes in the vacuum line of your cruise control by starting the engine and opening the car hood. Listen for signs of vacuum leaks. If you hear a sucking sound then the vacuum lines connecting the actuator and the control module is worn out or damaged. If you cannot hear any sucking sound, visually check the vacuum lines and look for leaks. Have your leaking vacuum lines replaced by an auto mechanic.

Step 4 - Check the Throttle Linkage

The throttle and the actuator mechanism of your car’s cruise control system are connected together with metal chains called the throttle linkage. The throttle linkage can easily break away when driving on rough terrain disabling the control mechanism of the control module. The throttle and the actuator mechanism are normally found beneath the accelerator pedal. Using a floor jack, lift your car and check if the metal chains connecting the actuator and the throttle have broken away. You can easily solve this cruise control problem by replacing the throttle linkage.