I have a 2004 Silverado and the alternator is not charging. Took the alternator off and got it checked. the alternator work find. the gage cluster went out. And was told the computer may be bad. something about the FCM and the PCH???? Need help bad..l...

 

Have you checked the 175 Amp Littelfuse Mega Fuse? On a 2004, I believe it's located on the side of the fuse block under the hood. You should see a red cable coming from the battery straight to the Mega Fuse and another red cable coming off the other side of the fuse. The fuse might be a different brand but search for Mega Fuse to see what it looks like.

If the battery was accidentally jumped in reverse, or accidentally arced, this fuse could have blown.
Also, there was a tsb for the 2007-2009 models regarding the mega fuse and arcing between the terminals and the fuse. I know it's a different year but I'd check for corrosion and arcing as well even if the fuse checks out okay.

 

I look for the 175 Amp mega fuse. I don't have one..

 

What I would do is starting with the positive lead coming off the battery, anywhere a positive lead is screwed or bolted to something, remove the screw or nut and make sure there is no corrosion. If there is, clean it up good with a light abrasive. Do the same with the negative cable.

If you pop the cover off of the fuse box under the hood, you don't see something like this attached to the front of it? This is the Buss brand. It might be 125 Amp instead of 175 Amp.





Are your backup lights, directionals and other lights inside the vehicle working?

There's also a small ground wire on the back on the engine block that can cause strange issues.

Could be a corroded or loose ground strap.

 

yes the backup lights, directional, and inside light are working, put will flash on and off. checked the ground wire on the back of the engine block, that was find. I didn't see a 125 or 175 amp fuse in the box under the hood.