Q: Jeep will not start when hot

With starting conditions it’s important to differentiate between a crank no start and a no crank condition. These are two very different conditions with very different causes. A no crank is when the motor doesn’t turn. A crank no start is when the motor turns but won’t start. Both can be the result of failing components that can’t handle the heat.

With a no crank condition, this is usually the starter. The starter sits very close to the motor and gets very hot. It is not in use when you are driving but it is steadily getting hotter as you drive. Once you stop an attempt to restart the car, its internal connections won’t allow the flow of electrical current. This is a factor of electrical theory which I won’t go into depth about here.

With a crank no start condition, you have a similar condition with heat but the affected component will be a module or other electrical component. All electrical components suffer from this weakness. To determine what has failed will require the recreation of the symptom. This can be hard is a shop environment. Driving the equivalent distance to create the condition can be time consuming and costly. Problems can’t be diagnosed when they are not actively failing.

If you’d like some help with these checks, I recommend having a certified mechanic, like one from YourMechanic, perform an inspection of your no start condition.

Good luck!