'98 burb, voltage issues

[nikwho]

My wifes truck is a '98 suburban. We love the truck! A few weeks ago it was seemingly not regulating the voltage well. headlights would surge at stop lights(idle) and any use of electricity(power windows, loud music etc.) would cause the headlights to dim. Being a internally regulated, I replaced the alternator. Later that night we went to the grocery store. Ran great and when we came out she turned the key and nothing. So i popped the hood and the neg. battery cable was just a tiny bit loose. tightened it and she turned right over. Its run great for the last couple of weeks and yesterday, she took the kids to a movie and it was really hard starting afterwards. Alternator was charging at about 14.5 volts.... Use of power would yeild a deflection in the volt meter on the dash. I was checking over everything and he single wire that plugs into the top(not the charge wire, but the single 14ga. or so wire with a plug) would deflect the volt meter when pushed or manipulated. DIdn't really seem to be the problem though. Any help would be appreciated! Thanks, Nik

[nikwho]

Im not sure about the age or condition of the battery. Have not had it load tested yet, but doesn't seem like the root of the problem if the alternator is charging at over 14 volts. Hopefully you guys can shed some light for me! Maybe the cause of the starting problem, but if the alternator is charging at 14 volts, the condition of the battery is irrelevant while the system is running and charging, right? Sounds like something else to me!

[Restrorob]

The small wire with the plug is switched power, It energizes the alternator when the key is turned on so it will put out. A bad connection there can cause intermittent out-put, You should also go ahead and get the battery load tested as well just to deem/eliminate it as a problem.

[Stano]

I have had similar occurances with my 96. Finally took it to parts store and found that the alternator while producing 14 volts it is only producing 36amps. It is a 100 amp alt. I am going to have to replace it soon but it is keeping the battery up and its starts every day. I also had a drain that would take the battery out after a couple days of sitting it was the vanity light in the drivers sun visor the switch wasnt depressing all the way. Then after that happened I got another drain that would take it out after a few hours. When I put my cold air intake in I hit the underhood light I guess and bent it the light would come on when I parked the truck facing uphill. Both of these occurances I discovered at night when I was going to the truck and after I would get in it. You might look at these, could be causing a drain that makes it hard starting.

[nikwho]

Well, it sounds like it has compounding problems. I think that we're definately getting a drain from the passenger side sunvisor light. There is not a good connection with the switched power wire and i still need to check the amp output on the new alternator and load test the battery