I have a 2007 f150 lariat with the 5.4L. Last weekend the alternator went out on it, since I had it tore apart decided to do the plugs on it as well. Got the plugs out in changed, put a new alternator, tensioner pulley, and belt on it. Started it up took it down the road a few miles everything was good. Pulled it back in the shop changed the oil, got into it started it up and was gonna pull it outa the shop and the check charge system message came across the info screen. Left it running popped the hood and started looking everything over seemed fine. Went and checked the battery post and the one wire that is bolted onto the back of the alternator that comes up to the battery was hot, like starting to melt the wiring hot! Shut the truck off and checked all connections and nothing was loose. So my question is what could be causing this? Another thing is that the guy that owned it before me had a aftermarket alternator on it that said stinger and said it was putting out 200 amps, and the wire that bolts to the back of the alternator has voodoo wiring printed on it, so I'm guessing that's not stock either. I'm kind of lost here and don't know what could be the problem.

 

Anyone have any ideas?

 

I bet the last owner did the "big 3" mod to the charging system. You should check the starter wires, battery and chassis grounds for any issues.. Corrosion can cause resistance and that could create the heat your describing. Is the battery an AGM? Or lead acid? That alternator you took out might still be good if you discover you just have a grounding issue. Search for the "big 3" mod here on the forum or on google for pics.

 

Thanks for the help! I will go check the starter, and all ground connections when I get to the shop. Ya it's looking to me he did do the big 3. There was a 2 gauge wire going from the alternator to the battery. I just have a motorcraft battery. With the old starter I checked it by unplugging the positive battery post when it was running and the truck died.

 

Well I ended up checking everything over again and again still the same. So I ordered a new factory alternator harness from the ford dealership, replaced that and went for a drive. The check charging system came back on again. So I took off the new alternator took it back to the parts store and got another new one. Put that on and the truck is fine! Put on over 50 miles and no lights no nothing! After putting the 2nd one on I realized that it don't wine as bad as the first new one did. So I'm gonna say something wasn't right with that first new one.

 

Thanks again especial86 for your help!

 

Your welcome bud! Glad to see you figured it out! Those damn reman alternators can really be hit or miss. Its a good thing you caught that!

 

Here is the cobbled up wire mess the guy before had on my truck. Was just like this one my truck with some electric tape hold the middle together.

 

Then he had the other wire that bolted to the back of the going to the battery too.

 

I like the wire of multiple colors! Nothing like just hodgepodgeing the system together. Glad you have that cluster flub fixed!