I have a 2007 Jeep Grand Cherokee Laredo, 4X4; 6 cyl gas 3.7 L; automatic with 56,000 miles on it. I started loosing power and all the warning lights came on. I took it to a mechanic and he replaced the wheel speed sensor and the electronic shift control. I took it home and lost power again. It wouldn't go any faster than 30 mph. I pulled over, turned it off, restarted it and it ran find for about three miles at which time it lost power again. The next morning it wouldn't start. I attempted to jump it and although the lights and radio would come on, it wouldn't even turn over. We towed it to the mechanic and he couldn't find anything wrong with it other than the battery was dead and needed to be replaced. Could the battery be causing the loss of power?
Sounds typical of the alternator not working. It is common for it to be intermittent but not at such low miles. The next time you catch it acting up, use an inexpensive digital voltmeter to measure battery voltage while the engine is still running. You must find between 13.75 and 14.75 volts. If it is closer to 12.0 volts or less, you should have seen the gauge on the dash going down and a battery warning light turn on. If the voltage is too low, we'll have to head to the two small wires on the back of the alternator. Measure the voltage on both of them, but that must be done with the engine running.