Hi guys, (and Ladies of course)

Has anyone else had this;

My 2006 GMC... Dual alternators, dual batteries.

1. Voltmeter shows between 9 and 14-volts, checked batteries, found loose post on drivers-side battery, bought two "Sears Platinum" batteries. (100-Month Warranty)

2. Six months go by, no problems... then start-up one AM and the voltmeter shows between 9 and 14-volts, I run the RPMs up to 1500, after 1 - 2 minutes the gauge moves to above 14-volts and (then after reaching 14-volts) the DIC says "Battery Not Charging" and the Battery-Light comes on. I drive toward the Dealer and the DIC goes out. I leave the truck at the Dealer and the next day they tell me the problem was "The passenger-side battery post was not torqued down properly". ($60) :o:

3. Three days later, same thing happens. I take the truck to the Dealer, the next morning the Dealer calls and says "There is acid leaking from the passenger-side battery" (No $) so I take the truck to Sears. The Sears guy says "It can't have a leak because these are No-Maintenance batteries." They check the batteries and the charging system and say everything is fine. :rolleyes:

4. Two days later, same thing happens. I take the truck to the Dealer and the service-writer brings out the mechanic and shows me a "Wet" battery-post, and says "It's leaking". I take the truck back to Sears... I insisted on speaking with the service-manager and asked for a new battery... I get a new battery. ($12 for labor) :p:

5. The next morning, the same thing. (Battery not charging) I take the truck back to the Dealer. They show me a "Bulletin" that describes my problem and says I need to have them replace a "175-Amp" fuse. ($40 - Not covered under warranty) :mad:

6. The next morning... guess what... same problem. I took the truck in to the Dealer and said "Don't call me until it's fixed".

7. I get a call from the Dealer; they said "We think one of your alternators is Over-Charging and causing the problem... We'll call you back when it's finished" :cool:

So... What do you think? Is this something strange or what? :eek:

Has this happened to anyone else?

My next call is to the "Regional GMC Rep"

Thanks, :(

Kemosabe

"We think one of your alternators is Over-Charging and causing the problem... We'll call you back when it's finished"


Nail:Head.

Me thinks the diode bd in one of the alternators has pooped, overcharging your batteries just like the dealer overcharged you.....:(

Decades ago when I worked at a golf course, the cart chargers would foul and overcharge the set and a tell-tale sign was electrolyte overflow. You ought clean the entire area with baking soda and a good rinse.

BTW, did you get the 175A fuse the said was "bad"?

Nail:Head.

Me thinks the diode bd in one of the alternators has pooped, overcharging your batteries just like the dealer overcharged you.....:(

Decades ago when I worked at a golf course, the cart chargers would foul and overcharge the set and a tell-tale sign was electrolyte overflow. You ought clean the entire area with baking soda and a good rinse.

BTW, did you get the 175A fuse the said was "bad"?
Posr #5 here http://www.dieselplace.com/forum/showthread.php?t=256152
but the pics are gone. The techlink bulletion requests the torque to be checked at the fuse studs.

On an '06, I would personally disassemble the bolts and spacers from both battery positive cable terminals. Having had a "post terminal" leaking has most likely resulted in corrosion under the spacer. It comes out just like the bolts do (friction fit). Corrosion at that spacer in the double positive connection is where I'd put my money.

Keith,

First the "Overcharging" is a little strange... The voltmeter shows (around) 10-volts for at least 2-minutes before the meter reads 14+. Second the voltmeter moves (about) 1-volt "back and forth" which seems to indicate the regulator is working... I don't see an "Overcharge"...

With regard to the "Fuse"... The Service-Writer said they replaced a 125-Amp fuse with a 175-Amp fuse... Weird... the fuse that was in there was good. The "Service Bulletin" said to do the replacing.

:cool:

The low voltage is after startup is due to the glowplug/ preheat sequence and some voltage drop is normal. Your voltage is too low after startup due to a faulty battery connection, again, most likely at the position that had a leaking terminal.

x2 on heymccall