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Old 06-03-2020, 07:04 PM   #1
danger1138
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Member#: 279525
Join Date: Apr 2011
Chapter/Region: Tri-State
Location: QUEENS NY
Vehicle:
06 Fxt

Default Is this a sign my alternator is bad? 06fxt

I got that red intermittent battery light on the dash come on yesterday driving back home. Car seemed to run fine all the while.
Today i took my car to auto parts store and charged up my battery. It was low. They charged it back up, tested it. The machine and service rep both said the battery held the charge fine.
I installed the battery back in my car. 06 fxt.
The car started and ran fine. Read 13-14 battery volt on the cobb v3 ap. Halfway home I again got the dreaded battery light on my dash. Toggled with cobb accessport to read the battery volt., it was at/around 11.2 while cruising. Car felt sluggish at that point.

My theory is that the battery (when fully charged), is fine, the culprit here is the alternator. Bad alternator not working properly adversely draining my battery while car is running.

- i have checked the fuse in engine bay compartment. Not blown.
- i removed green plug from alternator, turned ignition to on' position and no lights appear on dash. That means.. something in my favor.
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Last edited by danger1138; 06-03-2020 at 07:10 PM.
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Old 06-04-2020, 12:44 AM   #2
SlammedSix
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Join Date: Apr 2015
Location: 07 STi/ 08 STi/ 15 STi
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I am looking at the wire diagram from a 06 FXT it should be the same on your car.

Pin#1 is a Black/White wire and this wire is there to send B+ to your cluster to turn off the battery light. When the alternator is not outputting voltage on this wire the battery light will illuminate on the dash.

Pin#2 is a Blue/Red wire and this wire gets B+ with the key on. This is the signal that activates the magnetic field for the alternator to be able to produce power when spinning. This wire gets B+ from Fuse#3 in the engine compartment fuse box its a 10amp fuse.

Pin#3 is not used
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Old 06-04-2020, 05:36 PM   #3
Cougar4
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2001 LL Bean Outback
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You most likely have a bad alternator. See if you have battery voltage on the two small wires while the engine is running. If you then check to see if the main output wire of the alternator goes to a slightly higher voltage than the battery when you rev the engine slightly. If the voltage does go higher then the lead going to the battery has a resistance problem. If the output voltage just stays what the battery voltage is then the alternator is bad.
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Old 06-13-2020, 06:37 PM   #4
danger1138
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Swapped alternator with a used working one and it solved my issue. Battery voltage back up to 13.5 while cruising now.
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Old 06-13-2020, 09:14 PM   #5
Cougar4
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The 13.5 volts you saw is at the low end of the good charge scale. The upper end is about 14.8 volts. If the voltage goes lower than 13 volts while driving check the connections of the charging system and make sure all of the connections are making good contact and the connections are snug tight. If the voltage is still on the low end then I suggest you have the alternator output tested to see if can produce the full rated output it is designed to do.
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Old 06-15-2020, 08:56 PM   #6
SubieDoobieRu
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do a charging system test, sounds like you have a bad alternator tho. At the very least on its way out. Test both the battery and alternator, then replace alt and belt at the same time. Unless belt is fairly new. also make sure your tensioner is good as well. Could be loosening up over the drive.
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Old 06-16-2020, 10:43 AM   #7
danger1138
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06 Fxt

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Quote:
Originally Posted by Cougar4 View Post
The 13.5 volts you saw is at the low end of the good charge scale. The upper end is about 14.8 volts. If the voltage goes lower than 13 volts while driving check the connections of the charging system and make sure all of the connections are making good contact and the connections are snug tight. If the voltage is still on the low end then I suggest you have the alternator output tested to see if can produce the full rated output it is designed to do.
Voltage was at or about 13.5 while cruising, may have been higher. Ill double check this afternoon.
Quote:
Originally Posted by SubieDoobieRu View Post
do a charging system test, sounds like you have a bad alternator tho. At the very least on its way out. Test both the battery and alternator, then replace alt and belt at the same time. Unless belt is fairly new. also make sure your tensioner is good as well. Could be loosening up over the drive.
I lucked out. Purchased this used alternator, so far so good. Went to auto parts store to get battery inspected/ charged. Turns out i had a 3 year warranty on it, so was replaced with a brand new battery. Also new belts to boot.
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Old 06-16-2020, 03:20 PM   #8
danger1138
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06 Fxt

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just checked my battery voltage on cobb ap v3. While cruising its at ~13.7 to 14.12
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Old 06-16-2020, 03:29 PM   #9
Cougar4
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Winestone

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You should be fine with those voltages. You could have a load check done on the alternator to see if it can produce its' rated output current but as long as you see those readings you know the battery is getting a good charge to it.
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