Troubleshooting a Semi That Won’t Start

When you’re about to head out with a load and your semi truck won’t start, the last thing you want to deal with is a major delay. Fortunately, there is a good chance you’ll find what is wrong and get on the road fast with a little bit of troubleshooting. Get your truck back to roadworthy conditions with these steps.

Check Your Cables and Sensors

Semi trucks are a maze of cables and sensors that you learn about during truck driver training. All it takes is a cable to shake loose or a sensor to go out for your truck not to start. Double-check these components to make sure nothing is out of place. If you spot an issue, reconnect or restore the problem part, and your truck should be ready to go. Don’t forget to pay close attention to your battery connection.

Look into Your Ignition Lock

Many drivers use ignition locks to protect both their semis and the valuable goods inside of them. However, if you fail to disengage the lock properly, it could end up preventing you from driving away. If your truck won’t start, make sure all of the security equipment is properly disengaged, so you can get on the road.

Wait for Your Glow Plugs

Many diesel trucks have glow plugs that have to be warm for the truck to run. Glow plugs generally heat very quickly—usually without you even being aware that it is happening—but sometimes the process can take longer. This is especially true of your truck has been parked somewhere cold. Even if the temps are cold, your glow plugs should warm up in about 30 seconds. Keep cranking for 30 seconds or so, and if the truck suddenly comes to life, your glow plugs were likely just taking some to get warm.


At Yuma Truck Driving School, we give you all of the tools you need for a career as a driver, from learning to troubleshoot your truck to building your skills at different types of driving. Find out how to enroll by calling (888) 647-3239.