I have a 2005 F-150 Lariat. I will start from the beginning. Last late winter the check charging light came on and my voltmeter would start to dip, my lights would dim, and eventually my whole dash would turn off, but the pickup would still be running. Then it would snap out of it and the dash would come back on and all gauges would go back to normal. This happened a few times. Some times it wouldn't come out of it and the pickup would eventually die. I first had the alternator checked at and it said it was bad so i bought a new one. A couple days later, i had the same problem. I read some online forums about this problem and nobody seemed to have a solution. I read one that said the PCM might be going bad. I found a PCM and brought it and the pickup to a dealer to program it and install it. The check charging system came on 1 time after that and then it seemed to be fine all summer and fall. Now that it got cold again, i'm having the same issues. I have had the battery load tested, the alternator is putting out 14.4 V, the cold battery reads 12.49 V. It was just acting up yesterday so i called the local car shop and we put it on a scanner. A code came up that there was a short or open circuit from the alternator to the ground or alternator to the power. I have checked continuity between everything i can think of. It seems like the cold has something to do with this problem. I parked it inside and had the battery charging and started it, it seemed like it would run just fine. I pulled on wires and wiggled everything around and i couldn't get it to screw up so i decided to park it outside for a while and see if that would get it to screw up. after about 4 hours of being out in 25 F temperature, i went out and checked the battery voltage. it was 12.49 V. I turned on the lights to put a load on it and watched the voltmeter. After about 30 seconds of having the lights on it started draining really fast and i couldn't start it. Any help would be greatly appreciated. I have read a bunch of forums with people having the same issues, but nobody ever posts if they found a solution to the problem.

Thanks in advance

 

Sounds like the battery is going bad. You need to find some place that can do a REAL load test, not just one of those hand held jobs.

Believe it or not the Walmart where I live has a very good machine to test the batteries.

 

I have tried 3 different batteries now.