ok hopefully somebody will read this and go "your problem is..." but im not gonna get my hopes up.

ok the battery light has been coming on in my truck. when it does i check with a volt meter and the truck running only off the battery. if i unplug the alternator cable from the battery and test it i get like 0.1 volts. while truck is still running i touch the alternator able to the battery terminal and the voltage output immediately returns to normal(14.x volts). reconnect everything and the truck runs fine for a while. then randomly the battery light will come on again and i have to disconnect the cable, reconnect it again and its fine for a while.

what could cause the alternator to suddenly give almost no volt output, and return to normal as soon as its reconnected and the system draws power from it? is it something that can be repaired? i dont want to have to spend $200+ for a new alternator

 

i would take it to a speacialist were they can test it. alternators can be rapaired but you need to find a good repair shop

 

If it's a 2005 like you post indicates, why not take it to the dealer?

 

well i installed the roush s/c and installed myself so im expecting a hard time from the dealer on any warranty issue... plus with the s/c and new pullies really make it trickie to get the alt out i think i might try to take it up there and see if they can at least test it for me

pic of alternator removal nightmare:

 

These are the things you get into by doing the mods that you have on a vehichle in warrenty.
You have to accept what results.
If you put underdrive pullies on, that will contribute to the problem but it sounds like the regulator has a fault. Playing with the cable shocks it into temporary operation.
Take it off and have it tested or the dealer will charge you for the labor.
If you bought ESP warrenty, they will not warrenty the engine or trans with a blower on it. It's in the book.
Good luck, they will hang you for anything thay can to get out of it.
I had one new tire chop on the front but because the lower ball joints were worn-- no dice.

 

Alternators need a voltage feed to work, i.e. no output unless supplied with battery voltage. Try cleaning your battery cables for a start. I believe that these alternators have an internal regulator, it could be a problem with that. Check battery voltage w/ alternator disconnected, then hooked up. If it increases, then your alternator is charging. Also, check connections on the inline mini-fuse on the org/lt bl wire running to the alt, and the 175A mega fuse feeding upstream from this wire and also from the yel/wh wire. Intermittant faults often caused by loose wires. Also, make sure that you didn't disconnect an engine ground when installing SC.

Dan