Kenworth T680 Cruise Control Problems with Quick Reliable Solutions!

kenworth t680 cruise control problems

Last updated on April 12th, 2023 at 03:21 pm

The cruise control system is basically part of your vehicle’s electrical system that controls the speed. It is designed to take over the throttle and maintain the steady speed that is set by the driver. Still, it is important to remain a vigilant driver since there are some problems that could cause the cruise control to fail. 

There are four main problems that could result in a failing cruise control system. These problems are a blown fuse, the speed sensor broken, a failing brake light or brake pedal switch, or problems in the electrical system. To diagnose any of these, you are required to have your vehicle inspected and the issue diagnosed. 

This article highlights some of the common problems you are likely to encounter with your Kenworth T680 cruise control and possibly how to fix some of them. Read on. 

Kenworth T680 Cruise Control Problems and Reliable Solutions

kenworth t680 cruise control problems

The cruise control is a very convenient feature especially when you are on the highway or taking a long drive. All you need to do is set the speed, and relax with the knowledge that the vehicle will maintain the speed.

There are even modern cruise control systems that allow the driver to maintain the speed and a safe following distance with the vehicle in front of you. This is why when the cruise control fails, it is very annoying. And when it fails suddenly, it becomes dangerous. 

Cruise control on Kenworth T680 is controlled through the vehicle’s computer or ECU. With that in mind, there are several common problems that you may encounter with your cruise control system. 

Bad Fuse 

As earlier mentioned, the cruise control system is controlled by the ECU. And just like many electronically controlled systems in the car, there is a corresponding fuse for the cruise control.

This fuse is designed to blow to protect the system in case there is an impending short circuit. Therefore, if your cruise control system stops working, it could be attributed to a blown fuse. 


It would be best to have a mechanic inspect your vehicle. He will use a code scanner to connect to the vehicle’s ECU. This enables the mechanic to read the trouble codes to diagnose the problem.

If it is a bad fuse, then the mechanic will go ahead and find the fuse corresponding to the cruise control system and check to see if it has blown. If that is the case, the fuse is removed and replaced with the right fuse rating in amperage. 

Failing Brake Pedal Switch

Usually, the brake pedal switch will turn on the vehicle brake lights upon sensing that the brake pedal has been pressed. Typically, the cruise control system is set to disengage once the brake pedal is pressed.

This means that the cruise control is also connected to the brake pedal switch. Hence, if this switch fails, the car may think that the brakes are still engaged. This will cause the cruise control system to fail altogether. 


In this case, it is also advisable to have a mechanic inspect the vehicle. You can start by examining the brake pedal switch for any superficial damage. Then, you can check the wiring that is connected to the switch and make the necessary changes. Once the switch is replaced, the brake lights and cruise control should be back in working order. 

Damaged Vacuum Actuator/ Cable/ Hoses

On the older vehicle models, the cruise control speed is maintained by employing a vacuum actuator and cable that is connected to the throttle.

In the event that the vacuum hoses are damaged or the vacuum actuator stops working, then the cruise control system will also fail. Also, if the cable that connects the actuator to the throttle breaks, the system will also stop working.


To check for a damaged vacuum actuator, you will have to open the hood and locate the actuator. Check for any damaged hoses and/or cables. If the issue is with the actuator, it will have to be replaced. 

Failing Speed Sensor

Speed sensors play different roles in a vehicle including regulating fuel flow, indicating vehicle speed, and regulating ignition timing. By extension, the cruise control system significantly depends on the speed sensors since it is required to maintain a certain set speed.

If the speed sensor on your Kenworth T680 fails, then the cruise control system is also highly likely to fail. Moreover, the speedometer is also likely to stop working and you may notice that the engine experiences difficulty when idling. 


If it is an issue with the sensor, an experienced mechanic will have to go underneath the vehicle. Once underneath, try and locate the sensor and examine it as well as the surrounding wires checking for any damage. Also, ensure that the wires from the sensor connecting to the speedometer and cruise control are not frayed. 


Adaptive cruise control is basically a smarter version of the normal cruise control that drivers have grown accustomed to in their cars. This newer version is designed to employ cameras and sensors from several safety systems to monitor the traffic around it and maintain safe distances. Unlike the previous cruise control system which maintained a speed until the driver intervened, the adaptive cruise control slows or even stops the car on its own when necessary. 

The cruise control system works to automatically control your car’s speed. It helps drivers to avoid the temptation of exceeding the speed limit. Moreover, it comes in handy in preventing driver fatigue on long distances. 


The cruise control system is a convenient feature in most vehicles. However, you may notice that this system suddenly stopped working altogether. Outlined above are some of the reasons that could cause issues with the cruise control system. Hopefully, this article helps you diagnose and fix the issues. 

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