1995 Ford Mustang Battery draining

03 Mustang GT (Parasitic) Battery Drain Fix

Hello,
I am seeing a lot of mustangs are having battery draining issues and I wish to share some simple solutions found while working on a friends 03 GT 4.6ltr.

In a quiet area, key switched off, hood up, Listen carefully close to alternator. I heard a high pitched hissing/whistle sound at low volume, came from back of alternator. This sound was the voltage regulator/rectifier staying on when key is off due to faulty diodes inside the voltage regulator/rectifier circuit, can cause battery to go dead after car not ran in about 2-7 days.

After having the alternator tested free at a parts store, test showed alternator was good because the faulty diodes in the alternator did not show up on the test, the machine did not test for faulty drain back issues that were present.
Alternator on-car-fix:

There was battery voltage running at all times through the two-wire connector on back of alternator. Disconnect the battery first for safety and to reduce chance of short circuit. The yellow wire/with white stripe is hot while car is off so I traced this from the 2-wire connector on the alternator then closer towards driver side front fender. Next I cut the Yellow/White Stripe wire, spliced a good connection wire to it and ran it through a hole in the fire-wall to the fusebox(under dash), connected it to a 15a fuse that does not get used but has power when key is turned on but no power when key is off.

The purpose for re-routing the hot wire to the alternator, is to turn off the alternator charging circuit when the key is turned off so it may not run down the battery. I am seeing good results with this fix(or patch) so far. No More Parasitic Battery Drain!

Another fix can be to change the small pulley on the alternator to a larger pulley so the alternator does not spin too fast, putting too much energy through the diodes can cause a charging system to act a fool. So if you have charging issues and have an alternator changed, putting a larger pulley on can make sense turn into saved dollars(especially on high revving engines).

I hope this info helps to solve some draining battery and/or alternator issues.

for reading,

TyBorg1

Disconnect your car battery for 30 minutes. Plug it back in.

check for water damage on the computer. it sound like a mustang i fixed a few months ago. the customer broke the windshield and the body control computer got wet. so the car was cranking itself or turning lights on when raining until running battery out of charge. he could not drive vehicle on rainy days until 2 or 3 days later. this car wasn t convertible but since u said they change the winshield i could be leaking water.

Could be several things. The battery or alternator can be tested at most of your local parts store. I would start with those probably battery first then alternator as batterys are less expensive and earier to install. What ever u decide to do i would make sure to get both checked to avoid burning up a new battery if it is the alternator as well as the battery.

Check the major connector to the cluster and ing switch issue can cause wird things

You May Have Had A Vacuum Line That Controls The Climate Controls When Sliding The Vent Control Back And Forth From Floor Defrost And Vent Can You Here Any Noise Like Doors Closing Or Opening in The Dash

get a knife switch on the battery , it will complete ly disconnect the battery. then at leats you wont have to charge it. thats all i got youll still have to set the locks etc. perhaps you could get the alarm system deactivated.

Hey how long has it been doin this???? Drain your gas COMPLETELY! and let it sit with cap off for a couple of hours so if there is water in there it can drain or dry out. If that doesnt work make sure youe battery cables aren't loose. Rplace spark plug too.

the fuse box is located at the bottom of steering column cover

Disconnect pos. battery cable for 3-5 minutes, then reconnect that should do it!!!!!!!!!!!!!