Ok so for a little while now I have noticed that the dummy light for the battery has been coming on, also noticed that the actual gauge for the battery is riding lower than it should. Has been starting normally even as cold as its been at night. So today I stop in at Auto Zone on the way home from work and have both tested. The battery has a small amount of crud on the post but checks out good and then start her up and she is running 14.2 on the tester. So he tells me it's not the altenator but could be a bad cell in the battery. I decide to try cleaning the post once I get home and see what happens. On the way which is about 12 miles the light stays on the entire time and then the ABS light comes on,then the seat belt light comes on, then the radio quits, the tach stops working and the speedo is doing who knows what. I have the window down and try to put it up and the truck jerks and I know better than to try it again. As I pull up the drive it tries to die and I gimp it on up and park it. Tried to roll the window up and she does indeed die. I have done nothing to it yet. WTF is the problem????

 

sounds like a altenator

 

x2

 

even though it tested good???

 

yea samething happened to me and i got a new alternator

 

ok I guess thats what I gotta do. Thanks

 

if the light is coming on, then the alt. take it off the truck and get it bench tested. it's more accurate than their boxes they take to the vehicle.

 

sounds like alot of effort hell if i got to take it off i may as well go ahead and replace it

 

definitely alt

 

and it doesnt matter what kind of voltage the alternator puts out... if its not putting out any amperage no work can be done

 

Could be the alt, but one thing I would check first is the ground cables in the engine bay, I was having similar problems and i found a loose ground cable along the driver side fender inside the engine bay. Tightened it up and my problems went away.

 

Thats on my to do list dude at work said the same thing. Thanx

 

Grounds are the most important part of the electrical system so as stated above check, clean and tighten all of the ground points.

Then check the battery/alt again and see what happens.

When Auto Zone checks an Alternator or battery, they do a load test which puts a strain on the system. This is turn will (sometimes) excite an alternator or battery enough to get a good reading for a little while then things will crap up again !
When checking the grounds, start at the battery cables, then the battery ground point, then the frame/block points, also with a multimeter check to see if the alternator case is grounded back to the battery grounding on the fender.

Also, if/when you replace the alternator consider doing the battery too, unless it has been replace earlier and don’t forget new cabling from the alternator to the battery and as much of the ground wire as possible and go one size larger if you can.
Sounds like a lot but putting in a new alternator/battery is nice and will work ok for a wile but if the current can’t flow then the system will not work well for long.

Luck

 

This exact thing just happened to me(to a T) The advance auto parts guy said my napa battery(came with the truck) had a bad cell and that in turn killed my alt. bench testing the alt showed 10 volts. i replaced the alt 95 amp and the battery(better one not a cheapie) All is good for now but i will check those grounds for peace of mind.