Why is my cruise control not accelerating?
Most often, cruise control won’t accelerate because the engine or throttle control isn’t responding to the cruise request due to a fault in the throttle actuator, fuel delivery, or safety interlocks such as the brake switch or transmission signals.
How cruise control works and common failure points
When you set a speed, the cruise control system asks the engine control unit to open the throttle enough to reach that speed. If the engine cannot meet the demand—due to power loss, defective throttle control, or a safety interlock—the car will hold at current speed or fail to reach the target.
Key components involved
The following parts interact to control throttle, monitor speed, and enforce safety. A fault in any one of them can prevent the system from accelerating to the set speed.
- Electronic throttle control or throttle-by-wire system (throttle body actuator)
- Brake switch and clutch switch (safety interlocks)
- Vehicle speed sensor and wheel-speed/ABS sensors
- Cruise control module and engine control unit (ECU)
- Wiring, connectors, and the CAN bus network
When any of these parts experiences a fault or calibration issue, acceleration to the set speed may fail.
Common causes when cruise control won’t accelerate
Below are the most frequent issues that prevent cruise control from increasing speed. They are grouped into engine/throttle problems and electrical/safety interlocks.
Throttle and engine issues
These problems relate to the engine’s ability to generate enough power or respond to throttle input.
- Failing throttle actuator or electronic throttle control (ETC) system
- Engine misfire or weak ignition causing power loss
- Fuel delivery problems (faulty fuel pump, clogged filter, dirty injectors)
- Air intake restrictions (dirty air filter, clogged intake, vacuum leaks)
- Exhaust restrictions (blocked catalytic converter) reducing power
Electrical and control-system issues
These issues involve sensors, wiring, and control modules that guide cruise control decisions.
Before listing, this paragraph explains that faults in sensors, switches, and the control network can prevent acceleration, even if the engine itself seems healthy.
- Faulty brake or clutch switch that disables or misbehaves the cruise control
- Faulty vehicle speed sensor (VSS) or ABS sensors affecting speed feedback
- Cruise control module, wiring, or ECU fault; CAN bus communication errors
- Damaged wiring or corrosion in connectors
- Software/firmware issues requiring an update or reflash
In many cases, these issues are interrelated and a professional diagnostic scan is needed to identify the exact fault code and component.
Diagnostic steps you can take
Before you start, remember that basic checks and an OBD-II scan can reveal the most common faults. If a fault code points to throttle control, sensors, or module communication, focus there. Always prioritize safety and avoid driving aggressively if power loss is present.
- Check for warning lights and retrieve fault codes with an OBD-II scanner; note any codes related to throttle position, misfires, or speed sensing.
- Test throttle response: on modern vehicles you won’t see a physical linkage move, but you can observe whether the throttle command responds to pedal input via a scan tool or by the actuator’s behavior.
- Inspect brake and clutch switches; a stuck or faulty switch can prevent cruise control from engaging or accelerating properly.
- Check the vehicle speed sensor and related wiring; a flaky VSS can cause incorrect speed feedback and poor cruise performance.
- Inspect for vacuum leaks and intake restrictions (for vehicles with vacuum-operated throttle or older systems).
- If codes point to throttle control or sensors, consider software updates or professional diagnostics; avoid driving long distances if power loss or misfires persist.
These steps help narrow the fault to a specific subsystem. If the problem remains after basic checks, schedule a professional diagnostic and repair, especially if warning lights are illuminated or performance feels unsafe.
Summary
When cruise control cannot accelerate, most often the issue lies with engine power delivery, throttle control, or safety/interlock systems. Start with an OBD-II scan to read fault codes, verify throttle responsiveness, and check safety switches and speed sensing. If simple checks don’t resolve the problem, seek a qualified technician to diagnose and repair underlying faults, as ignoring the issue can lead to reduced drivability or unsafe conditions on the road.
How do I know if my cruise control fuse is blown?
There are two places on the back side of each fuse to probe; if the test light does not light on both sides of the fuse you will find that the fuse is most likely blown. If the test light does not light on either side of the fuse; you will need to look in the owner's manual to see what that circuit feeds.
What is the most common failure of a cruise control system?
The most common failures in a cruise control system are often due to a faulty brake light switch or a blown fuse, according to several sources. Other frequent issues include problems with the speed sensor, a loose or broken cruise control cable, and general electrical or vacuum leaks.
Common failure points
- Faulty brake light switch: This is a very common cause of failure. A defective switch can signal to the system that the brake is being applied, causing the cruise control to disengage.
- Blown fuse: Cruise control systems are protected by fuses, and if a fuse blows, the system will stop working. This is a simple and inexpensive fix, so it's a good first thing to check.
- Damaged speed sensor: The speed sensor is critical for providing the system with accurate vehicle speed information. If it's damaged, the cruise control won't function correctly.
- Broken or loose cruise control cable: The cable that connects the system to the throttle can become damaged or loose, preventing the system from working properly.
- Electrical issues: Since cruise control is an electrical system, other problems like faulty wiring, a bad cruise control switch on the steering wheel, or a malfunctioning vacuum-actuated switch can cause it to fail.
Other potential causes
- Traction control system: If the car's anti-lock braking (ABS) or traction control systems are not functioning properly, they will often disable cruise control as a safety measure.
- Dashboard warning lights: A "check engine" light or other dashboard warnings can also disable the system.
- Adaptive cruise control sensors: For modern adaptive systems, external factors like bad weather, a dirty windshield, or a blocked radar sensor can cause the system to deactivate.
Why sometimes when I press the gas pedal it won't accelerate?
Your car may not accelerate properly due to a variety of issues, such as a faulty throttle position sensor (TPS), clogged fuel filter, or a problem with the transmission. Other common causes include a dirty air filter, a malfunctioning oxygen sensor, or a failing catalytic converter. A simple and immediate check is to look for any objects, like a golf ball or mat, that might be physically stuck under the gas pedal.
This video explains how to diagnose common reasons for a car not accelerating: 57sCar Computer ExchangeYouTube · Feb 1, 2024
Potential causes
- Faulty sensors: A bad throttle position sensor (TPS) or oxygen sensor can send incorrect information to the car's computer, leading to poor acceleration.
- Fuel system issues: A dirty or clogged fuel filter, or a failing fuel pump, can prevent the engine from getting enough fuel to accelerate properly.
- Exhaust system problems: A clogged catalytic converter can restrict exhaust flow, causing a significant loss of power.
- Transmission problems: Issues like a slipping torque converter or problems with solenoids in the transmission can make the car feel like it's not accelerating correctly.
- Air intake issues: A dirty or clogged air filter can reduce airflow to the engine, leading to a loss of power.
- Ignition problems: Worn-out spark plugs or faulty plug wires can cause misfires and slow acceleration.
- "Limp mode": If there is a serious sensor or system failure, the car may enter "limp mode," a safety feature that limits engine power to prevent further damage.
- Physical obstruction: It's possible something is physically blocking the gas pedal from fully depressing, such as a floor mat or an object on the floor.
What to do next
- Check for physical obstructions: First, check under the gas pedal for any foreign objects that may be preventing it from moving freely.
- Check for the check engine light: If the check engine light is on, a diagnostic scan can provide clues to the specific problem.
- Consult a professional: Because there are many potential causes, it is best to have a mechanic diagnose the issue, especially if the problem is intermittent or the check engine light is on.
This video demonstrates how to reset the throttle position sensor (TPS): 25sMechanical SpecialYouTube · Apr 16, 2025
What is the main cause of cruise control not working?
Common reasons for cruise control not working include a blown fuse, a faulty brake light switch, or a bad speed sensor. Other issues can be related to electrical problems, such as damaged wiring or a faulty cruise control switch, or a Check Engine light being on. For adaptive cruise control, a dirty camera or sensors can also be the cause.
You can watch this video to learn about the common reasons why cruise control might not be working: 58sMaxTheCarGuyYouTube · Feb 24, 2025
Common causes
- Blown fuse: A blown fuse will interrupt the electrical current to the cruise control system, preventing it from working.
- Faulty brake light switch: The cruise control system is designed to disengage when you press the brake pedal. A faulty switch can send a continuous "brake" signal, or the cruise control may not work if it can't detect the brake pedal being pressed.
- Bad speed sensor: The speed sensor provides information to the cruise control system. If it malfunctions, the system will stop working because it doesn't have accurate speed data.
- Electrical issues: Damaged or loose wiring, or a faulty cruise control switch on the steering wheel, can prevent signals from being sent correctly, as can a problem with the vehicle's main computer or electronic control module.
- Check Engine light is on: A problem with the engine or a related system will often automatically disable the cruise control as a safety precaution.
- Dirty or blocked camera/sensors (Adaptive Cruise Control): If you have adaptive cruise control, dirt or obstructions on the front-facing camera or radar sensors can prevent the system from working correctly.
- Vacuum leak (older vehicles): Some older cars use a vacuum-operated system. A leak in this system can cause the cruise control to fail.
This video demonstrates how to check the brake light switch: 57sAuto Repair GuysYouTube · Oct 7, 2019
