Battery light on dash

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Sep 27, 2015 | 04:33 PM

2005 Ex Limited

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From: Shoreview, Mn

Battery light on dash

This ID10T light came on last weekend, and I just started trying to fix this.

I found this post, https://www.ford-trucks.com/forums/1...shuts-off.html, but this isn't my problem.

The alt is old, but tested good four times at Napa. Battery is three years old, and it's holding good charge. My scan gauge 2 is showing 11.4-11.6, and I'm guessing this is what's throwing the code, although there isn't an actual code.

I don't have the money to go just start replacing parts, and I need this truck for next weekend, 10/3/15, so I hope to find something by then.

At 2000rpm the SC2 is still showing 11.6 volts, so would it be the charging system? Volt reg? Something in there is clamping the voltage down. At 18 years old, and 250k miles I'm not afraid to put new parts into.

Sep 27, 2015 | 05:44 PM

Bluegrass 7

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The battery isn't being charged from the alternator.
That's the only place charge comes from.
Check the plug going on the alternator for bent pins and good seating.
The dash light comes on when the alternator regulator puts a ground out on the lamp lead because the alternator is 'not outputting' to remove ground as your alarm lamp signal for trouble..
Unless you find an issue outside the altenator, I would not trust the alternator testing you got.
You make the decision.
.Good luck.

Sep 27, 2015 | 05:51 PM

2005 Ex Limited

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From: Shoreview, Mn

Quote:

Originally Posted by Bluegrass 7

The battery isn't being charged from the alternator.
That's the only place charge comes from.
Check the plug going on the alternator for bent pins and good seating.
The dash light comes on when the alternator regulator puts a ground out on the lamp lead because the alternator is 'not outputting' to remove ground as your alarm lamp signal for trouble..
Unless you find an issue outside the alternator, I would not trust the alternator testing you got.
You make the decision.
.Good luck.

The pins were clean on both connectors, and the power stud was also very clean given it's age. I know the light is back fed from the system so when you lose the 12v from the alt the potential of the battery actually turns the light on.

I'm more inclined to believe you that the bench test at Napa is too broad whereas on the truck it needs something much more controlled. $165 for a new Napa (not sure who makes them for Napa; recommendations?) 130 amp, and if this is the direction you would go yourself then it is good enough me.

Sep 27, 2015 | 06:59 PM

03f15012

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I put a reman. in mine when the light came on. Pretty much knew it was the alternator as the light flickered and went out when I revved it up.

Sep 27, 2015 | 07:15 PM

Bluegrass 7

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Just to be sure you understand; the dash light is already powered from 12 volts through the ignition switch.
The regulator grounds the circuit when there is 'no output' from the alternator to open that ground.
Good luck.

Sep 27, 2015 | 08:10 PM

2005 Ex Limited

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From: Shoreview, Mn

Correct. One side of the battery light is from the alternator and the other comes from the battery.

Sep 27, 2015 | 09:21 PM

PineyMountainRacing

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Any shops around that will rebuild it for you, might be less money, plus you can get a 2nd opinion? Most of the ones around here will finish it up that day or have it ready for you the next morning.