OK, reader's digest version:

2002 FX4 ext cab 4X4 Lariat 5.4

Driving to the boat ramp, battery light came on. Odd....never done that before.

Headlights begin to go dim. Back into the water and turn the headlights off, because truck is about to die. Load the boat. Wife gets in to pull the truck out, turns the lights on, truck dies. I jump it off and have enough juice to pull the boat out and then it dies. Clicking noise when i tried to turn the key after that. had to have it towed home.

Question: What the heck is it? Should I try to replace the alternator?

thanks,
brad

 

yup.

 

Check the cables on the alternator for fraying around the terminal, should just check all the battery cables while you are at it, both ends.

If you can have the truck down, pull the alternator and battery and have them tested.

I am guessing the belt was not slipping the whole time causing this, so I am looking in another direction for the same symptom.

 

Thanks for the replies. I have not even looked under the hood yet in the daytime. I will investigate tomorrow afternoon. there was corrosion around the battery terminals. i will take the battery to get it tested first and go from there. i will also look at all the belts.

thanks guys.

 

Anytime I see corrosion, I pull the battery caps. If I see low cell electrolyte or sulfating, I replace the battery - I don't even bother to test it.

But, when the engine's turning, the electrical supply is coming from the alternator, not the battery. So, that makes the alternator suspect.

But, if the battery has an internal short, it will not hold a charge and, it will "suck up" the output of the alternator.

My bet's on the battery at this point.

- Jack

 

Oreily says it is the Regulator. They said the alternator itself it Ok. He can order just thre regulator piece that goes on the back of the alternator. it is $40. an Alt. is about $160. Your thoughts?

btw, i replaced the battery today. The battery the truck calls for, the one i bought, is almost twice the size of that pos that was on it. what is up with that. Used car dealer?

 

Maybe, could have been the previous owner though.

If you CAN replace the regulator without replacing the alternator, I say do it. SSCULLY, what do you think? (You're the expert, not me). :o

- Jack

 

instead of towing it, you could have thrown the boat battery in the truck and drove home, a good ways, even if the alt is dead.

 

Just have a buddy hook jumper cables to your truck and let it charge for a while, then you can drive it home and work on it there. Slap a new alternator in it and you're good to go. It's easy to replace.

Your old battery may even be fine, although you have probably been running on it for days, and that's not good for it.

A good battery's voltage takes a while to drop enough for the batt light to come on. Kinda misleading too. The light means low voltage. Not "bad battery".

 

Hey guys, thanks for all the info. The truck has almost 170k miles on it, so i decided to replace the alternator. It was fairly easy. I have a few busted knuckles to show for it. Runs great now and starts like a top! Hopefully it will see 300k now.
Thanks again.