Okay, here is a strange one. I have a 2002 4.7lt dak. This last week I have had a strange electrical problem. My check gauge light comes on and when looking at the gauges the gauge for battery power is not registering, I have power to everything, and I am driving in the dark and have plenty of lights and power. Once I stop and turn the truck off I can start it back up without any problems and the gauges are all reading again.
I cleaned the posts and this seemed to work for a few days and then the problem got worse (I cleaned the post several times after the light came back on again after the first cleaning). Then this morning I was headed out and the check gauges light came on again. But before I could get the truck home all of the warning lights came on and I had just enough headlights to get home. When I first got home the truck would not start after I shut it down like it normally does, however I went back out about an hour later and she started right up.
I have changed the battery clamps, traced all of the wiring and have found no problems, I have also had the battery and alternator tested and they are both fine, I am also not throwing any codes for a quick diagnoses so I do not think it is any of the sensors. I am at a loss of what to check for next. I am hoping someone might have some suggestions on where to look next to fix the problem.

 

Where did your get the alternator and battery tested? If it was with a hand held test meter at a parts store, you could still have battery or alternator problems. The hand helpd test meters at the parts store do not always give accurate info. Was the alternator and battery still installed on the engine, or did you remove them and bring them in the store to have them bench tested? That is the best way to check both.

You can also get a decent idea of the battery's condition with a volt meter, it should have at least 12.5 volts on it at rest with the engine off. Then to check the alternator, start the truck but have no electrical accessories on. Battery voltage should be at least 13.5 on up to about 14.5 volts when measured across the battery terminals. Then turn on the AC at maximum cold temp, blower fan on high speed, headlights with the high beams on, fog lights too if you have them, and the radio. When you turn on all of these accessories, the voltage at the battery should stay the same, 13.5 to 14.5 volts with the engine on and accessories on too.

If the voltage is less than that, you may have a bad alternator or possibly a bad voltage regulator. The voltage regulator is an internal part of the PCM, the only way I know to test it is at the Dodge dealer with their DRB III scan tool. A parts store can load test the battery if you bring it inside the store to their test bench. Your battery may have a dead cell, and that is not always easy to diagnose with the battery still in the truck. A load test will help narrow it down.

Dakota's are very sensitive to low voltage problems. Having only even 11.5 volts on the battery or charging system will freak out a Dakota's electrical system. This sounds to me more like a battery or alternator problem. If the voltage regulator was bad you would be having continuous electrical problems all the time and the truck would probably not run or start at all.

Check your grounds too. Dakota's are also very sensitive to bad grounds. I don't know about 4.7's but on my 3.9 there is a ground lug on the front of the engine, one in front of each valve cover, plus there is a ground lug behind the left front wheel on the frame, and there is a ground lug in each fender well behind the headlights. Clean all your grounds to shiny bare metal with a wire brush. If the ring terminal connectors are corroded cut them off and crimp on new ones. Also check the cable on the back of the alternator and make sure it has a good clean connection.

Jimmy

 

I have the exact same problem as the guy who originally posted this. I replaced the battery 2 1/2 months ago, so I doubt that it is the cause. I had the alternator tested both ways, in the vehicle with the hand held meter and removed from the vehicle and bench tested. Both times the alternator tests good. I really need some help here as this is my only vehicle and I commute to work.