the battexery light on my 2002 6.8 comes on @ low speeds. Has a new e battery and the cables are good. I'm thinkin alternator, but it was tested recently and I was told it's good. Any ideas?

 

Just last week I had to replace alt and got an intermittent batt light, tested everything including the new alt "which tested good" and cleaned all my connections everything tested good so on a wild hair the dealer swapped me out for another alt and that fixed it. mine is a diesel though

 

Take it somewhere else and have it tested. My guess is they found the alternator was putting out current/voltage that was within factory spec..AFTER it hit a certain RPM. It's not uncommon to have a low rpm issue and have it clear up at the higher speeds. Have it rechecked, and have them test the power at idle as well as at "target" rpms.

 

The alternator was tested @ idle rpm. I believe it was around 13.8 or so.

 

disconnect your battery with it running, check voltage then.
13.8@idle should be fine as far as the voltage. I have a 250amp alt in mine, I have to be about 800rpms about idle for max output(14.6).
I'm sure sure however how what the computer will read in the gassers in order for the lights to come up. May just be reading low voltage, or it may have a hall effect that senses the current, hopefully somebody else will know for sure on your model.

 

Same exact thing happened with my Ex a few months ago. Light would stay on while in low rpms and would flicker and eventually shut off after driving it for a few miles. I swapped out the Alternator and issue was gone. Easy swap. Took longer driving to pick it and get back home then it took to actually unbolt and reattach.

g/l

 

yeah idk what to think. It was having starting issues but that was cured with a new battery sometime back. I plan on a 2 week trip this summer and would like to resolve all issues by then. On a side note, I got this beast with the intention of a cummins swap and while that is still the long term plan, the V10 is impressing me. I might keep it until it dies.

 

it's exactly what mine was doing before I put in the big alt. Especially with the starting issues you were describing. Could be either the old battery sped up the process in killing the alt, or vice versa. A good high amp alt can be purchased for about the same cost as you can grab one from your local parts house.

 

trust me - you want to swap the alt. When it finally goes, and it will be without warning - you won't be able to get the car jumped and will end up having to pay for a tow and a new battery along with a new alternator... Bite the bullet - new alternator for me was about 125 out the door with a lifetime warranty.

 

I agree, Ive gone through 3 on my Ex. if you test at idle it will show good. Test under load, turn all your lights on etc. it will fail. Get one with a lifetime warranty they are easy to change.

 

agreed they are prolly not testing it under load

 

thanks for all the replies. I will try and get a new one tonight.