Battery light comes on
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Joined: Aug 2003
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Battey light comes on
Hey Everybody!
Quick question. I have a '99 F-150 Ext-cab 4.2L V-6. I've noticed recently that whenever I stomp on the gas hard whether from a complete stop, going uphill or merging onto the interstate and the RPMs hit about 3000 or higher between shifting gears, my battery light will flicker on. When the tranny shifts the light goes out.
I am woner if it is telling me that I have a weak battery or a faulty alternator. Anybody have any thoughts?
Ralph
Quick question. I have a '99 F-150 Ext-cab 4.2L V-6. I've noticed recently that whenever I stomp on the gas hard whether from a complete stop, going uphill or merging onto the interstate and the RPMs hit about 3000 or higher between shifting gears, my battery light will flicker on. When the tranny shifts the light goes out.
I am woner if it is telling me that I have a weak battery or a faulty alternator. Anybody have any thoughts?
Ralph
Senior User
Joined: Dec 2003
Posts: 245
Likes: 3
From: north minnesota
sounds like to me a loose serp belt causing the belt to slide over your alternator pulley until you step on it causing the serp belt to tighten and grip the pulley...................just a thought
Lead Driver
Joined: Mar 2004
Posts: 5,372
Likes: 108
From: Northern Indiana
When I bought my 97 with 94000 on it did the same thing and I had the dealership replace the altenator and the problem was solved.
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Senior User
Joined: Dec 2003
Posts: 383
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From: Mililani, Hawaii
sounds to me like the belt is slipping, or the alternator is on te way out...I would say try changing the belt first, if it has not been done. check the tensioner pulley also...as well as the other pulleys.
are there any other signs of alternator probs...like dimming lights, hard starts, or other electrical probs?
are there any other signs of alternator probs...like dimming lights, hard starts, or other electrical probs?
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Joined: Aug 2001
Posts: 4,532
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From: Trussville, Alabama
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Joined: Jul 2003
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Had the same problem on a 99 F150-5.4. Got so bad the light stayed on and battery started to drain. After replacing the alternator and still not getting 14+ volts to the battery, started really checking things out and found bad fuse for the 12 volts that supplies the built in regulator on the alternator. Put a new fuse in but still had battery light until we wiggled the fuse in it's socket. Tightened the prongs for the fuse and has been fine ever since. Theory is, the connection was marginal and whenever it was stressed, it would break connection causing the regulator circuit not to work and then the blinking light and the fuse finally blew probably from slight arcing at the poor connection. Before replacing the alternator, check for a loose fuse in the fuse block on the driver's side inner fender. Not sure what fuse number but was a 20A on ours and is probably the same on yours. Owners manual might have a fuse ID for it.
Good luck!
A. G.
Good luck!
A. G.
Senior User
Joined: Jan 2004
Posts: 227
Likes: 0
From: Tulsa, Oklahoma
Same problem. Only now, since I went from
255/70R16 to 265/75R16 the other day,
the light stays on most of the time the vehicle
is moving, whether accelerating or not.
When I'm sitting still it doesn't come on.
There does appear to be some dimming during
acceleration and also when trying to open both
power windows at once, the window motors bog.
I'll look at the brush pack and alternator first,
unless someone tells me different.
'97 F-150 Supercab 4.6 127,500
'99 F-150 Eddie Bauer Expedition 5.4 85,500
255/70R16 to 265/75R16 the other day,
the light stays on most of the time the vehicle
is moving, whether accelerating or not.
When I'm sitting still it doesn't come on.
There does appear to be some dimming during
acceleration and also when trying to open both
power windows at once, the window motors bog.
I'll look at the brush pack and alternator first,
unless someone tells me different.
'97 F-150 Supercab 4.6 127,500
'99 F-150 Eddie Bauer Expedition 5.4 85,500
Last edited by FourthFordTruck; Mar 15, 2004 at 09:56 AM.
Senior User
Joined: Jan 2004
Posts: 227
Likes: 0
From: Tulsa, Oklahoma
My alternator was bad. The brush pack was almost non-existant.
I could have tried just a new pack, but since I had it off, and
didn't want to take it off again if it weren't the pack, I did the whole thing.
Replaced with lifetime warranty alternator from Autozone.
I could have tried just a new pack, but since I had it off, and
didn't want to take it off again if it weren't the pack, I did the whole thing.
Replaced with lifetime warranty alternator from Autozone.