I believe this is my alternator so just looking for maybe some conformation! When driving normally lights are fine but when I run full throttle and start reaching high rpm before the shift point my headlights dim probably to near half their normal brightness. As stated would seem to me to be the alternator, I have just replaced the battery bout 1500 miles ago. The truck is a 99 screw factory all the way. Bulbs are Sylvania silver star fairly new.

Many Thanks
Craig

 

Maybe belt slip, when was it changed last ?

When you hit the WOT shift, how long is the squeal ?

Easy enough to pull the alternator, and see if it is having a high RPM output, but on would think for that short amount of time, the battery would pick up the slack ( only talking about 10 to 20 seconds ). Maybe I am missing something on that, any additional accessories or modifications ?

 

Thanks SScully,

Have done no mods to the truck, it has no squeal at shift point and the belt is new as of six months ago!

I stopped by three auto parts stores that do the free check on elec. systems and all said the alt checked out good. One of them said let me get the other guy who knows more than I do and we visited and then he pulled on the belt and said ah-ha to easy to pull it up like this (he was getting a couple of three inches slack)

I believe you nailed it with your first rattle I need a new tension-er on there and happen to already have one as it was making a little noise last summer in the heat that went away over the winter. I think the centrifugal force is moving it away from the pulley enough to allow the belt to slip at high rpms, it is kind of funny that there is no belt squeal though. I will get it on there and see and then post back.

Again Many Thanks
Craig