Battery Light on
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New User
Joined: Feb 2010
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Battery Light on
I have an 06' F-350, 6.0 that is having electric issues. I put a new alternator on last week which seemed to fix the battery light but it only lasted 3 days & now the battery light is on again. I have had the alternator & batteries checked & they all checked ok. Anyone have any suggestions????
Post Fiend
Joined: Jul 2005
Posts: 6,127
Likes: 6
Batteries need to be:
A) removed from vehicle
B) charged fully
C) load tested separately with a realistic load similar to what a diesel starter imposes.
One major issue: Alternator wiring - pigtail and also battery / alternator connectors.
Check link below.
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Test alternator output (voltage and current with a clamp on ammeter).
Give us data on voltage:
a) sitting still after 12 hrs no run / charge
b) key on, glow plug cycling
c) key on after 2 min
d) cranking
e) immediate voltage when engine catches
f) voltage at 30 sec intervals to 5 min after start.
It should be in the 14ish vote range then.
A) removed from vehicle
B) charged fully
C) load tested separately with a realistic load similar to what a diesel starter imposes.
One major issue: Alternator wiring - pigtail and also battery / alternator connectors.
Check link below.
------------------
Test alternator output (voltage and current with a clamp on ammeter).
Give us data on voltage:
a) sitting still after 12 hrs no run / charge
b) key on, glow plug cycling
c) key on after 2 min
d) cranking
e) immediate voltage when engine catches
f) voltage at 30 sec intervals to 5 min after start.
It should be in the 14ish vote range then.
Thread Starter
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New User
Joined: Feb 2010
Posts: 18
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I have the charger on the secondary battery tonight. I will check it in the morning while the primary battery is charging. I hit them with a load tester while hooked in circuit & they both tested bad so I will isolate them & check. I had the new alternator tested & it is good according to the tester. Thanks for the input.
Post Fiend
Joined: Jul 2005
Posts: 6,127
Likes: 6
Roger that.
The older battery that is good is often fine for use in another car....
Mark:
If you are reading... the batteries that "dont test" for your truck is the perfect batteries for your inverter ---
free, and it is "good enough" for the job.
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New User
Joined: Feb 2010
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Replaced both batteries & the light stayed off for an hour & then back on. As I stated before, I had the alternator tested & now 2 new batteries but no cure yet. I guess it will head to the shop tomorrow to get a full diagnostics on it.
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New User
Joined: Feb 2010
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We tested the output of the new alternator & it is only putting out 11.5 volts. The old alternator when tested was acting funny & spiking weird. I have some corrosion on the trailer plug so I am wondering if that would cause this to short out. I have checked all the ground straps I could find & they were good & clean. The only conclussion I could come come up is the trailer plug.
Senior User
Joined: Sep 2004
Posts: 329
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From: Carroll County, MD
I am guessing alternator is the problem, especially if it is only putting out 11.5 on the test stand. On my 7.3, I went through 4 of them in about 10 days (was ugly). Also be wary of the control wires going to the alternator, not just the large power wire, and make sure the mounting area is clean, as the unit grounds through the body of the alternator to the engine.
The corrosion in the trailer plug on the back should have no real effect on the alternator, as all of those circuits are protected by fuses. A short would simply blow the fuse.
The corrosion in the trailer plug on the back should have no real effect on the alternator, as all of those circuits are protected by fuses. A short would simply blow the fuse.
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New User
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It was tested on the truck with it running. The weird thing is that the light started coming on while I was acclerating & then it would go off when I would stop at a light or sign. This is driving me nuts trying to figure this thing out.