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Took my truck out tonight or a little night ride. I haven't had time to drive it in over a month, so it did take a few extra seconds to fire up. I'm worried though that my alternator may be going south. It seems the voltage meter isn't going up to where it used to. I seem to remember the needle would hover in or near the green, then would dip a little upon starting, but would stay near the green when running. Now, it pretty much stays in the yellow arc. Is this a sign that I am not getting any charge to the batteries? I drove the truck for a good half hour tonight in order to charge the batts. Maybe because the headlights were on that the needle didn't move, but I am not sure. How can I tell if I am not getting any charge on the batteries from the alternator?

Hook a digital volt meter red lead to the battery cable that goes to the starter and black lead to ground. It should read 24 to 24.5. Now start the truck while watching the meter. It should drop to 22 to 23.5. While idling it should move back up to 24 to 24.5. Now race the engine to about 2000 RPMs and the meter should read 27.5 to 28.5. Less than that and she needs adjusting.

You also want to clean EVERY ground on the truck. Not just the battery grounds,but also the chassis grounds,and wiring loom grounds under the hood.

Chunk brings up a good point. Over my 55 years of wrench and meter bending I believe 70% of electrical issues were caused by loose or dirty/corroded connections or contacts.

Also...don't forget the woven bonding strap (ground) that connects the bell housing to the frame. Don't get lazy. If your already under the truck,get comfortable,and take your time. Un-bolt EVERY fastener that holds EVERY ground wire,bonding strap,or ground "anything" and scratch grind,or scrape any rust,paint,undercoating,etc off of the surfaces of the body or frame. Use what works...a screw driver,pocket knife,scotchbrite pad,moto dremel with a grinding stone,etc.Wire wheel the hardware to bare metal. Replace any hardware (bolts and nuts) that look questionable. Tighten the hardware firmly,and coat it with paint. Krylon OD paint works GREAT and repels water (don't believe me? Try it). Also check to see that your voltage regulator is grounded to the bracket on the fire wall (thats right...no paint where the mounting feet touch the bracket.) If all else fails ...like the generator tests,replace it with a "one wire" 24 volt delco-remy 10SI alternator. Twice the amp (50) and no more problems! BIG Plus you have the advantage of being able to completely reverse the installation back to stock configuration. Here's one right here>>> http://cgi.ebay.com/ebaymotors/New-Alte ... ccessories

Ditto what the guys said here. Make sure you have star washers on all of your ground cables as well. Clean up your contact points and use some die-electric grease on the hardware and connections. You have newer batteries right? Even so, ck the condition of each 12VDC batt. Good luck