Shuts off at will without warning

There are two common things to start with. The first is a failing crankshaft position sensor or camshaft position sensor. These commonly fail on any brand of engine by becoming heat-sensitive, then they work again after cooling down for about an hour. This usually occurs right after stopping a hot engine for a short period of time, as in when stopping for gas. While driving, natural air flow keeps the sensors cool. When stopped, "hot soak" allows engine heat to migrate up to the sensors and causes them to fail.

The problem with this is if you only have the crank/no-start problem, diagnostic fault codes might not set for those sensors. They often need more time, as in when a stalled engine is coasting to a stop. You do not need a scanner to read fault codes in the engine computer. Chrysler made doing that yourself much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds, leave it in "run", then watch the code numbers show up in the odometer display.

When there are no fault codes related to the crank/no-start, we will need to determine if the automatic shutdown, (ASD) relay is turning on during cranking. I will describe how to check for that if it becomes necessary. You will need a test light to measure the voltage at the ignition coil pack or any injector. Look for the wire that is the same color at all of those places. It iss usually dark green/orange. If either sensor has failed, this relay will turn on for one second when you turn on the ignition switch, but it will not turn back on during cranking. That relay feeds the ignition coil pack, injectors, alternator field, fuel pump or pump relay, and oxygen sensor heaters, so if it does not turn on, you will have a crank/no-start due to no spark, no injector pulses, and no fuel pump.

Since this occurs while you are driving, the better suspect is broken solder connections on the connector for the instrument cluster. Pounding on the top of the dash is not a scientific approach, but I just repaired one for this problem a few months ago, and that owner had kept the van going by doing that for over a year. I cannot remember if the starter would crank the engine, but if it did, it definitely would not start and run. As I recall, there were additional clues in that some of the warning lights were on or failed to turn on.

You do not need a scanner to read fault codes in the engine computer. Chrysler made doing that yourself much easier than any other manufacturer. Cycle the ignition switch from "off" to "run" three times within five seconds, leave it in "run", then watch the code numbers show up in the odometer display.