Hey guys I have a slight issue with my 2003 F250 6.0 pickup. Just started about 4 days ago where the battery light flickered on and off intermittently with no real pattern, but nothing happen besides that. I have an Edge Juice programmer and checked voltage through that because it happen while I was driving and everything looked fine sitting at around 12.9 which is pretty normal with my aftermarket stereo blaring and whatnot.

Next day, battery light was off when I left for work but when I got home, I went over all the connections and checked my voltages with my tester and they were sitting with the truck off 12.9 and 12.75 if I remember correctly. Since it went away I paid no attention and thought it was maybe just a loose connection.

Yesterday I gave my little cousin a ride to his friends house and while driving my stereo shut off and gauges kept on resetting, but everything else worked. I checked my voltage on my Juice and it would fluctuate between 13 ish to 15 almost 16 sometimes so when I went home I plugged my OBDII reader in and found 3 codes all of a sudden which was P1000, P0649 and P1379.

After using the trusty search button I have found what these codes entail but dont thing these codes would be the cause of my alt fluctuate like it did/does and my stereo shutting down.

Anyone have any ideas on what this could be ? I will note that a) I have replaced the alt at around 80k and my truck now has 110 which was about a year 1/2 ago along with 2 new batteries.

Anyways I appreciate your help in advance, I hope you guys can point me in the right direction asap because I only have tomorrow to work on it

J

Edit: Something I forgot to mention to you guys was that my truck runs just fine ... which is weird because otherwise with the codes thrown it shouldnt be running right ? and the check engine light never came on ...

 

P1000 is a interruption code from the PCM.

P0649 is some sort of cruise control error.

P1379 is Ford: (FICM) Supply Voltage Circuit High

I think you definitely have a power problem. Two of those codes are voltage related. The first one because the PCM probably lost power, and the last one because of a power spike. Late model Fords are famous for the gauges going crazy when there is a power problem also.

It may be a bad connection somewhere. I would do the old "take it apart and put it back together" trick on the alternator connections and the connections on the batteries and around the starter solenoid if you have one on the fender. Check any small ground wires you see bolted to the body.

This might be hard to find, but you might quickly stumble across it while messing around under the hood. Try to find out how the power distribution works from the batteries to the underhood fuse box and such, and check all those connections.

 

After doing some more reading and research, do you guys think it may be possible that the injector wires are causing the short since this is a 2003.5 and it was/ is an issue ... think this would do it ?

with all the wires under my hood for my lights, snow plow stereo and winch its not gunna be fun just searching

Funny also that I dont have cruise on my truck haha.

 

It is your alternator! Period! Replace it and don't do what I did and change everything else first.....And don't be surprised if you have to replace it 3 times more......

 

After doing a lot of playing around today on it, and checked everything that I have installed electrically, I do fully believe it is my alt, probably brushes I would assume which is causing the intermittent problem. Lucky for me when I purchased the alt last year, it came with a 5yr warranty from the shop, so I talked to my friend there and he's going to replace it and install it for me for free which is a bonus. Only downfall is I get it monday but I dont need to drive my truck on the weekend ... I just WANT to haha.

 

*update* so we replaced the alt on monday and still had this funky problem ... We checked the 3rd wire on the alt connection and we found we had ourselves a short because our resistance was changing from 51ohm - 111ohm - 0ohm.

we remedied this by pulling a single new wire to where the wire is attached to the gauge cluster and spliced it in. fixed the problem with the battery light on. but now we have the voltage still jumping up every once in a while past 15 ...

 

You should have a "A" wire(usually yellow) going to the alternator. This is the feedback wire to the regulator. It tells the regulator the system voltage, and it takes this info and adjusts the alternator output. I would check this wire over for the 15v+ problem.