alternator going bad?
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Tuned
Joined: Jun 2003
Posts: 489
Likes: 1
alternator going bad?
I've noticed that my battery guage drops from way above 12v to 12v when the truck is idling. If I have the fan on, or the lights, I can tell that I'm pulling from the battery. As soon as I rev it above 1000 rpm, the needle perks up to something like 16v and everything has more power and is brighter.
It didn't used to do this, is this a sign that the alternator or the voltage regulator or brushes?
It didn't used to do this, is this a sign that the alternator or the voltage regulator or brushes?
Cargo Master
Joined: Jun 2002
Posts: 2,033
Likes: 32
From: Aurora,Colorado
Have the battery "load tested" by Sears or someone else.
If the battery checks out alright when load tested-- directly check the battery-across terminals- when idling using a volt meter. If below 13 volts at idle with all electrical accessories on -and all connections are good-the alternator is bad or doesnt have enough capacity for the load.
If the battery checks out alright when load tested-- directly check the battery-across terminals- when idling using a volt meter. If below 13 volts at idle with all electrical accessories on -and all connections are good-the alternator is bad or doesnt have enough capacity for the load.
Senior User
Joined: Oct 2003
Posts: 480
Likes: 1
From: Elyria, Ohio
May; however check condition of cables; they can corrode internally; check continuity. Grounding connections clean and tight. Battery clamps and condition of battery (dead cell).
Battery at rest (engine off for 1/2 hour) should be 12.5 to 12.6 volts. Check voltage coming from just alternator with a DVM: should be between 13.5 to 14.5.
Battery at rest (engine off for 1/2 hour) should be 12.5 to 12.6 volts. Check voltage coming from just alternator with a DVM: should be between 13.5 to 14.5.
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