Check battery light help
Thread Starter
Joined: Nov 2009
Posts: 7
From: Florida
RAAAWWW lol but really the voltage regulator would be simple unplug, unscrew, and pop off i could tell you where the sensor is but i cant find my schematics for the mustang. if i find my book before anyone else posts where it is ill edit it in.Whenever you find the info, I'd appreciate it...
PONG
4th Gear Member
Joined: Nov 2007
Posts: 1,701
From: Florida
ok i found my book and checked the schematics and there is no sensor for the charging light its old school electronics. and only comes on when the alternators generator is not functioning. SO it could be the voltage regulator is bugging out and will only register bad if tested while acting up or some other problem with you alternator such as the brushes are wearing.
i attached the schematic for the charging section. as you can see by the right wire it's just to provide power/signal to the dummy light when low power the resistor represented by the zig zag line cause the light to illuminate, at the correct level the light is more resistant than the resistor causing the power to skip the light making it not illuminate. this is because power to take least resistant path.
the middle wire and the left wire on the schematic are for the charging and running power and are fused multiple time so i would also suggest checking the fuses listed in the schematic for partial blows, loose, or damaged contacts.
in the end if the replacement of the regulator doesnt solve the problem it is most likely time for a new alternator
i attached the schematic for the charging section. as you can see by the right wire it's just to provide power/signal to the dummy light when low power the resistor represented by the zig zag line cause the light to illuminate, at the correct level the light is more resistant than the resistor causing the power to skip the light making it not illuminate. this is because power to take least resistant path.
the middle wire and the left wire on the schematic are for the charging and running power and are fused multiple time so i would also suggest checking the fuses listed in the schematic for partial blows, loose, or damaged contacts.
in the end if the replacement of the regulator doesnt solve the problem it is most likely time for a new alternator
4th Gear Member
Joined: Jan 2008
Posts: 1,901
From: Greenville, NC
Being a much more technical version of what I said in the second post, I just didn't explain. 
I've tested many alternators that are bad on the car but wont test bad. My alternator just went out, but my light would only cut on under certain circumstances. First the brushes getting worn caused it to be random, and second, diodes went bad.
So I would definitely test all your connections, then go alt.
I've tested many alternators that are bad on the car but wont test bad. My alternator just went out, but my light would only cut on under certain circumstances. First the brushes getting worn caused it to be random, and second, diodes went bad.
So I would definitely test all your connections, then go alt.
Thread Starter
Joined: Nov 2009
Posts: 7
From: Florida
ok i found my book and checked the schematics and there is no sensor for the charging light its old school electronics. and only comes on when the alternators generator is not functioning. SO it could be the voltage regulator is bugging out and will only register bad if tested while acting up or some other problem with you alternator such as the brushes are wearing.
i attached the schematic for the charging section. as you can see by the right wire it's just to provide power/signal to the dummy light when low power the resistor represented by the zig zag line cause the light to illuminate, at the correct level the light is more resistant than the resistor causing the power to skip the light making it not illuminate. this is because power to take least resistant path.
the middle wire and the left wire on the schematic are for the charging and running power and are fused multiple time so i would also suggest checking the fuses listed in the schematic for partial blows, loose, or damaged contacts.
in the end if the replacement of the regulator doesnt solve the problem it is most likely time for a new alternator
i attached the schematic for the charging section. as you can see by the right wire it's just to provide power/signal to the dummy light when low power the resistor represented by the zig zag line cause the light to illuminate, at the correct level the light is more resistant than the resistor causing the power to skip the light making it not illuminate. this is because power to take least resistant path.
the middle wire and the left wire on the schematic are for the charging and running power and are fused multiple time so i would also suggest checking the fuses listed in the schematic for partial blows, loose, or damaged contacts.
in the end if the replacement of the regulator doesnt solve the problem it is most likely time for a new alternator
! I had posted on the other forum I belong to and no one had a good answer but now I should have it narrowed down.BTW, where in Florida are you?
PONG
Thread Starter
Joined: Nov 2009
Posts: 7
From: Florida
Being a much more technical version of what I said in the second post, I just didn't explain.
I've tested many alternators that are bad on the car but wont test bad. My alternator just went out, but my light would only cut on under certain circumstances. First the brushes getting worn caused it to be random, and second, diodes went bad.
So I would definitely test all your connections, then go alt.
I've tested many alternators that are bad on the car but wont test bad. My alternator just went out, but my light would only cut on under certain circumstances. First the brushes getting worn caused it to be random, and second, diodes went bad.
So I would definitely test all your connections, then go alt.
PONG
Gentleman's Relish
Joined: Feb 2005
Posts: 13,189
From: AZ
To the OP, under what conditions does the battery light blink/flash. On an 04 I find it doubtful you have corrosion problems.
Here's some first hand experience for you. I had a similar problem with my 00 V6. At WOT Like getting onto the freeway and under a heavy load sometimes with medium throttle (up hill), my battery light would blink/flash too. It WAS the alternator. I took it in off the car to test it. It passed the first time,failed the 2nd and 3rd time, passed the 4th time. Replaced the alternator given their equipment had just been serviced so I trusted it. Problem solved, no more light. I didn't have any other problems either (except for the lights would dim a bit at night if the light was flashing).
Most places that test your alt test it once and under ideal conditions (no heavy load or high heat). I had my car checked out with one of those machines that hooks up to the car and does put a load on it (but not much). It tested borderline.
I'm almost willing to bet the cost of the alternator that is the problem.
Here's some first hand experience for you. I had a similar problem with my 00 V6. At WOT Like getting onto the freeway and under a heavy load sometimes with medium throttle (up hill), my battery light would blink/flash too. It WAS the alternator. I took it in off the car to test it. It passed the first time,failed the 2nd and 3rd time, passed the 4th time. Replaced the alternator given their equipment had just been serviced so I trusted it. Problem solved, no more light. I didn't have any other problems either (except for the lights would dim a bit at night if the light was flashing).
Most places that test your alt test it once and under ideal conditions (no heavy load or high heat). I had my car checked out with one of those machines that hooks up to the car and does put a load on it (but not much). It tested borderline.
I'm almost willing to bet the cost of the alternator that is the problem.
4th Gear Member
Joined: Jan 2008
Posts: 1,901
From: Greenville, NC
NONONONO, don't go to autozone. Go to ford an get one. Idk about down there, but in NC, the part from ford was still less than the one from Advance (thats with my advance discount...)
And I just about promise you are going to have to return a reman. to autozone a couple times...
And I just about promise you are going to have to return a reman. to autozone a couple times...
Gentleman's Relish
Joined: Feb 2005
Posts: 13,189
From: AZ
I got my alternator from AutoZone. Zero problems I picked up the remaned lifetime warranty one. It had it on the car for about two years before I sold the car.
http://www.autozone.com/autozone/cat...dName=Duralast
I picked up the remaned lifetime warranty one. It had it on the car for about two years before I sold the car.http://www.autozone.com/autozone/cat...dName=Duralast
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