Cruise Control Failure: Causes & Solutions
Blown cruise control fuse Cruise control is an electrical system, which means there’s a dedicated fuse for it in your car’s fuse box. If that fuse has been blown, your cruise control button won’t do anything. Diagnosing this problem: Refer to your manual to locate the fuse box in your engine bay. With a cold car, pop the fuse box and remove the fuse dedicated to the cruise control. Either test the fuse with a multimeter or hold it up to a light source and inspect the wire inside to see if it is broken. Fixing the issue: Either see a mechanic or purchase a replacement fuse for your make and model. Insert the new fuse into the slot for the cruise control system and you’re good to go. Potential cost of repair: A new fuse shouldn’t run more than $10-30 unless you drive an exotic car. A mechanic will probably charge $100-200.
Faulty brake lights In many vehicles, the brake lights are looped into the same circuit as the cruise control unit. So, when a brake light goes out, it takes the cruise control unit down with it. Diagnosing this problem: Have a friend sit in your driver’s seat and press the brake pedal. Walk around your car and confirm the brake lights are working. Fixing the issue: If any of the brake lights are out, replace the bulbs. Your cruise control should come back on. Potential cost of repair: Seeing a mechanic for this will run $100 or so, plus the cost of the bulb. If you replace the light yourself, it shouldn’t cost more than $5-20 for the bulb.
Faulty brake switch The brake switch is the button connected to your brake pedal that actually engages the brakes. Because the brake lights are looped into the cruise control circuit, a bad brake switch may prevent the cruise control from coming on for the same reason a bad brake light bulb would prevent it. Diagnosing this problem: Have a friend sit behind the wheel and press the brake pedal to see what happens. If none of the lights come on—even after changing the bulbs—your brake switch is likely bad. Fixing the issue: A brake switch repair requires a professional mechanic, so take your vehicle to an automotive pro. Potential cost of repair: Luckily, brake switches are cheap and the repair is easy for a professional. Expect to pay roughly $75-100 depending on the shop minimum.
Damaged speed sensor Cruise control systems rely on a speed sensor to confirm (and maintain) the speed of the vehicle. If the speed sensor isn’t responding or working properly, the cruise control will not turn on as a safety measure. It may also turn on but shut off randomly whenever the speed sensor cuts out. Diagnosing this problem: Check your speedometer while you drive. If it isn’t working properly, the speed sensor is bad. Fixing the issue: See a mechanic to have the speed sensor replaced. Potential cost of repair: It depends on whether your speed sensor is embedded in the transmission or not. If it is, the repair may run up to $1,000. If it’s tucked behind your dashboard, it should only cost $100 or so.
Illuminated check engine light Some vehicles will shut down certain features if the check engine light is on (to prevent potentially catastrophic damage if the vehicle senses a serious error with the engine). Cruise control—which keeps the engine running at a specific speed—is almost always one of the features that won’t work. Diagnosing this problem: If your check engine light is on, it’s likely what’s keeping your cruise control off. Diagnose the issue by plugging in an OBD2 scan tool in your vehicle’s OBD port and running a scan to determine what the issue is. Fixing the issue: See a mechanic to have the underlying problem addressed (and the issue diagnosed, if needed). Potential cost of repair: The cost depends on the underlying problem. Something as simple as a new gas cap may only cost the shop minimum, but new spark plugs, engine damage, crankshaft failure, and other issues will cost much more.
Bad vacuum actuator The vacuum actuator is a complex device that monitors the difference between the air pressure outside and the air pressure in your intake manifold to adjust the engine’s settings for maximum efficiency. One of the settings it controls is the throttle control, which must stay locked in place for cruise control to work. If the actuator isn’t working correctly, your cruise control may turn on but your speed won’t remain consistent or stable. Diagnosing this problem: This is a tough issue to diagnose, but it will usually pop up in the error codes if you run an OBD2 scan. Fixing the issue: See a professional auto mechanic to have the vacuum actuator replaced. Potential cost of repair: The cost of the repair depends on the design of your actuator and whether it can be salvaged or not. It may cost anywhere from $200 to $2,000.
ECU/ICM errors The ECU (engine control unit) and ICM (ignition control module) work together to function as your vehicle’s computer. They take the data from your engine and vehicle components and then send it to the dashboard for display. If either unit runs into a bug or goes bad, it could potentially interfere with your vehicle’s cruise control functionality. Diagnosing this problem: Run an OBD2 scan to see if the ECU or ICM are throwing error codes. Fixing the issue: This is one of the more complicated issues you can run into, so see a mechanic to have them rewire a new ECU or ICM. Potential cost of repair: You’re probably looking at a $300-800 repair, but it can vary depending on the make and model of your car.
Broken cruise control button Sometimes, a crumb or a piece of dirt can get lodged in between the cruise control button and the steering wheel. If the button itself is damaged or dirty, you may not be able to turn the cruise control on. Diagnosing this problem: You should be able to tell if this is the problem just by testing the pressure of the button. Fixing the issue: You can normally pop off the cruise control button with a flathead screwdriver and then clean it or replace it. Potential cost of repair: A new cruise control button shouldn’t run more than a few dollars.
What happens if cruise control stops working?
Your car will simply coast as it normally would. Cruise control is more of a quality-of-life feature than an important function. You can 100% drive safely if the cruise control stops working. If it cuts out mid-drive, the vehicle will simply coast as normal and your speed will drop slowly until you reach the idling speed (if you don’t press the accelerator in the meantime).
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