2006 Cadillac DTS

WROMRO

MEMBER
2006 CADILLAC DEVILLE DTS
V8
2WD
AUTOMATIC
48,000 MILES

My digital voltmeter shows 12.8 to 12.9 during highway driving (even for long distances). I don't yet get any warnings but does this low reading mean the the alternator is geting weak or just that the battery is not taking the charge?

Monday, August 2nd, 2010 AT 2:37 PM

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

12.6 for a battery is 100% charge. If you are staying above that the battery is actually charging. The demand of the charging system may be low enough that you could see that. Try adding some load and see what happens, turn the blower on high, rear defog on, and the headlamps on high beam. See what this does to the charge output. If it gets lower, then you may have an issue. The newer charging systems are current controlled, and only provide when they really need to. This is to maximize fuel economy due to less load on the engine. If the battery is original, you may opt to have it tested as preventable.