Jim Grant's Tech Tips
Jeep Cherokee runs well 99.9% of the time. However, sometimes
when driving, it will go dead. Usually it cranks right up
when I pull to the shoulder of the road. Sometimes it will
run for days with no problems. Other times it goes dead
two or three times a day. I had it in the shop for a week,
but they could not find anything wrong with it. Any suggestions?
If your Jeep is shutting off like someone turned the key I would be critical of the crankshaft position sensor. While your Jeep is running you can unplug just about every computer sensor on the engine and it will still run, not great but run. If the signal from the crankshaft position sensor is lost on your Jeep, the curtain drops like a rock on that show. The fuel injectors, along with the ignition system, are shut right down. Just bang, end of show! While the crankshaft position sensor is off line from the rest of the vehicle, you can crank the engine over until the battery goes dead or the starter burns up, it's just not going to start. The next time this condition occurs on your Jeep, turn the ignition off and then cycle the ignition from off to on three times. On the third cycle leave the ignition in the on position. At this point watch the check engine light it should start to flash. If the code flashed is an 11 it is a good bet that the crankshaft position sensor has failed. So, the next time your Jeep drops dead, cycle the key and find out what the computer might have to share with you while you wait.