When I was on my way home from work this evening my truck lost all electrical power. My radio shut off first and then the windows would not roll up or down. Truck is a 02 screw 5.4L 4x4. Pulled the bat out took to parts store to see if it was the bat. It was low on charge and they are keeping it overnight to check the bat.

When I pulled into my condo lot all my gauges went dead and did not regsister anything. could not get it restarted so my wife and I had to push it back a couple of feet into my parking space.

What I am wondering is does this sound like a bat problem or is my alternator bad? My truck has 178xxx miles on the OEM alt.

If it IS the Alt how hard are these to change on the 5.4 liter? The last alt I did was on my ol stang w/ the pushrod 302 HO.

 

See what the battery comes back with after a load test.

Heat kills a battery quicker than cold, so it is this time of year when batteries will start failing.

Do you have any idea how old it is ?

After you get the results of the load test, you can make a decision about having the alternator tested

 

My bat was made june of 09 was put in july of 09 w/ the same weather STL is currently having hot and freaking humid as hell!!!!

 

Sounds like the alternator from past experience. Check the alternator field fuse (correct?) and make sure that's good first. You can check the voltage going to the battery and see where that's at. I keep forgetting, but if you take the negative connector off the battery, if the truck shuts off, or the positive one, see, can't remember. Someone want to clarify? As far as changing an alternator out, very easy.

 

Last year my truck was starting sometimes and others not. I figured it was because I had put some sound stuff in there. Battery was lot on juice or something. Turns out the alternator was not putting out any power. I ended up stuck at my friends work. We tried jumping it, but the battery wasn't getting charged enough to run the truck for more than 20 seconds.

The alternators are pretty easy to replace, you just need to know what you are doing.

 

BLUE20004X4 does make a good point, make sure BJB Fuse #11, 20A is good. Use a meter to check the pins on the back of the fuse on both sides. This is hot at all times.

the other thing to check is the alternator field wiring harness, I know JBrew has rebuilt at least 1 of these.

https://www.f150online.com/forums/el...nator-why.html

Something you can do while waiting for the results of the battery load test.

 

Well It turns out that it was the alternator. Luckily my father-in-law changed it for me as with the current heat wave I would have died changing it! LOL I don't have a garage currently and I would have had to change it in my condos parking lot!! I have noticed that my a/c seems to be blowing a bit colder too probbably due to the bat getting a full charge. I think it was going out for a while as when I would accelerate the a/c would seem to cut out a little and then come right back once I was crusing again.