Voltage drops when idling

[wreedps]

Hello,

My voltage drops to around 12.5 when idling at a light. I have really noticed it lately because the AC blower motor on high does not blow as hard until I hit the pedal to go.

I have a brand new ACDelco alternator and battery I just installed a few months ago. any ideas what this could be? Is there another part of the charging system I should be looking at?

 

[scottg918514]

Not 100% sure about NBS (800) trucks, but NNBS (900) have Battery Control Module (BCM?) which drops the voltage when in maintenance mode. I think I read that it helps with fuel economy, but not sure how since the belt is still on the alternator and spinning it.

But, long story short, it's normal.

---------- Post added at 02:53 PM ---------- Previous post was at 02:51 PM ----------

http://www.tahoeyukonforum.com/forum/showthread.php?t=23778

 

[BubZX]

I would have the alternator checked. u should be holding between 13.8 and 14.2

 

[scottg918514]

http://www.tahoeyukonforum.com/forum/showthread.php?t=52083

 

[wreedps]

Does this apply to the 05 Tahoe? I just got a brand new Delco alternator. The old alternator did the same thing. I dont think it is the alternator.

 

[scottg918514]

Can't answer that, hopefully someone else knows for sure. I'd guess that NBS trucks have the same BCM, or similar.

When u got the alt, did they say it had the internal voltage regulator?


Sent from my iPhone using Tapatalk

 

[NathanJax]

DOENSN'T apply to 00-06, they started that in 07

I would stop by a auto parts store. They can hook a little machine up and in 20 seconds tell you if you have a bad alt or battery

 

[01ssreda4]

12.5 is not normal, something is going on.

 

[SLCHOE]

Your alternator is not charging. Check the belt. If the belt is good and tight, you need an alternator.

 

[ccapehartusarmyINF.(ret)]

pull out your multi meter and start checking for high resitance in the battery cables
the positive batt terminal cable got a tad loose once on my vehicle wich was giving my similar voltage drops at idle