Dumb battery light
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Tuned
Joined: Jun 2004
Posts: 472
Likes: 4
From: Goodyear, AZ
Dumb battery light
So I just noticed I have the dreaded battery light come on the truck this afternoon... I tested voltage, and batteries are good at 12.7v with key off, and I start the truck, and voltage jumps up to 13.3-13.6. The voltage doesn't appear to change drastically with engine RPM or load, but the battery light does glow brighter with higher RPMs...
I assume it is the alternator as the batteries are Interstate batteries that are maybe a year old, and I have the extra heavy duty battery cables running from the Alternator to batteries.
Is there anything else I can test to verify? I'm pretty sure it's the wimpy 110amp one, so I figured now is a good time to invest in 140 with a pulley...
I assume it is the alternator as the batteries are Interstate batteries that are maybe a year old, and I have the extra heavy duty battery cables running from the Alternator to batteries.
Is there anything else I can test to verify? I'm pretty sure it's the wimpy 110amp one, so I figured now is a good time to invest in 140 with a pulley...
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Tuned
Joined: Jun 2004
Posts: 472
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From: Goodyear, AZ
FICM voltage still showed 48v and battery voltage showed 12.6-13v after I started it. I don't usually trust the scan voltage since it seems to differ so much more than anything else.
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Tuned
Joined: Jun 2004
Posts: 472
Likes: 4
From: Goodyear, AZ
Thanks Jack, I'll give that a shot.
I have a buddy who has a spare that I might swap out and see if it works... I want to upgrade to a 140amp alternator anyways, but the problem I have is do I order one (bocsh or Denso) or do I get one from Autozone (since it probably would be easier to warranty if any issues come back)
I have a buddy who has a spare that I might swap out and see if it works... I want to upgrade to a 140amp alternator anyways, but the problem I have is do I order one (bocsh or Denso) or do I get one from Autozone (since it probably would be easier to warranty if any issues come back)
Hotshot
Joined: Dec 2014
Posts: 17,834
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From: Jersey Shore
The light illuminates due to a voltage differential across the bulb, nothing more. DC or AC. PCM not involved.
Heres someone’s quick vid. It can be off the battery too, I just normally have done it off the source. Check both hot or cold, or whenever the light is on.
Heres someone’s quick vid. It can be off the battery too, I just normally have done it off the source. Check both hot or cold, or whenever the light is on.
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Tuned
Joined: Jun 2004
Posts: 472
Likes: 4
From: Goodyear, AZ
Swapped out the Alternator and all is back to normal... went with 140amp and noticed slightly higher voltages as well, so the old one was probably on it's was out.
Does anyone have a link on amazon or somewhere that I can get the smaller belt pulley for it?
Does anyone have a link on amazon or somewhere that I can get the smaller belt pulley for it?
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