trailbenz

Hello, what would be the voltage when driving down the road, and just idling. Thanks

tech2

depends on what model year you have...ecm controlled models have 6 charging modes.

If I had to pick a general number 14.4 is what you usually see.

trailbenz

Hey thanks, I have the l6 and now when I am driving OBD WIZ shows the voltage at 15.6 which seems high. Is it a bad battery or alternator?

Doug D

With engine idling or at speed voltage should be around 14.4 volts. Engine off voltage should be 12.6 volts.

15.6 volts is high. I would suspect the voltage regulator which in most modern computer controlled ignitions is in the ECM or PCM.

trailbenz

Well, I was wondering where the voltage regulator was, I thought it was on the alternator. So how do I find out if my pcm is bad?

kevinkpk

I'd not worry about it. That voltage is a little high, but have you checked it with a voltmeter? I'd suggest use a secondary test. The ecm controls the field voltage to the alternator, so you don't have a "voltage regulator".

trailbenz

The problem is my battery won't hold charge in the cold, yesterday after having it sit in 10 degree temps for 8 hours, it was just cranking over but did start. The battery is a replacement for one that lasted 3 years. I am thinking the battery again is the problem. Would that be true, just checked the battery this morning and it was at 11.8 volts which is really low from what I have read. Just try to make my life a little less stressful.

kevinkpk

Ugh yes. The more information you can post, the better response you will get from the bulletin board. Even if it is a 4 year battery.

tech2

+1 for posting the symptoms
-the charging systems will increase output when the battery is discharged.
-having the battery tested is the first step of charging system diagnosis.

does the battery go dead if not moved for days; if yes...check for a parasitic draw

trailbenz

Ya sorry for not putting everything out first, had to think about it. First the battery is just over one year old, and yes if I let it sit for a day it probably wouldn't start in the cold say 20 or below. Now the question of parasitic draw is my next thing, how do you find the source of the draw, I am ok with electrics but not great. That was going to be my next question, what are the common power draws when it is just sitting? Thanks for the input.