I am about to go crazy. I bought a 200W stereo from Circuit City and had them install it (my first mistake). They completely screwed up. My gauge lights wouldn't work, the stereo would not shut off when the car was turned off, and my battery kept dying. I took it back to Circuit City (my second mistake) to have them fix it, which the did. Or so it seemed. My gauge lights work, the stereo shuts off when the car is turned off, and after a new battery, which Circuit City reimbursed me for, everything was working fine. Except for the fact that my battery still keeps dying. I have replaced the alternator with a 65 amp, got a new Optima battery, replaced all the underhood wiring harnesses (which were in bad shape). The problem won't go away. The alternator is charging, so I guess something must be constantly draining the battery, even while the car is off. I even completely unplugged my stereo, and the battery is still being drained. PLEASE HELP! What could be wrong? I would prefer not having to charge my battery every week.
Electrical problems? PLEASE HELP
- Thread starter mxmattd
- Start date
2nd Mustang
Founding Member
I'm assuming this battery problem started after the radio installation, right? Did you also have a bigger amplifier for boost on the radio installed at the same time? What gauges, if any, are you using to verify alternator is charging sufficiently? 65 amp alternator really isn't that big of an alternator. Have you checked the voltage regulator, maybe it went south during the installation of the radio?
pabear89
Active Member
Start by isolating the drain on the battery,
remove the neg cable and install test light inline.
remove fuses till light goes out.
All fuses out and light still on, start unconnecting voltage reg,headlight switch ect.
PB
remove the neg cable and install test light inline.
remove fuses till light goes out.
All fuses out and light still on, start unconnecting voltage reg,headlight switch ect.
PB
2nd mustang : I didn't have an amplifier put in. All I am using is a 200W stereo with kick panel speakers and two 6" rear sony speakers. I'm still new to mustangs and cars in general, so I took my car to a guy I know that specializes in auto electronics. He told me that the alternator is charging ok past 2000 rpm. I replaced the regulator at the same time as the alternator. I asked the electronics guy about an alternator upgrade, but he said 65 was the most i could use for this car. Would I need to do anything in order to use a 130 amp or so alternator? I'm still not sure that the alternator is the problem, because the stereo has been out of the car for a few weeks, but the battery still drains. I am very confused and frusturated. Should i take the car to a real audio place and have it reinstalled?
pabear : as i said i am new to working on mustangs and cars in general, i defenately think that something is constantly draining, but could you give me a little more specific directions for finding the drain? I would really appreciate any help you can give me.
...at my wits end... ...nearly...
pabear : as i said i am new to working on mustangs and cars in general, i defenately think that something is constantly draining, but could you give me a little more specific directions for finding the drain? I would really appreciate any help you can give me.
...at my wits end... ...nearly...
Id upgrade to an internally regulated alternator and lose the external and its harness. Im using a 100amp 1 wire alternator on my 65. Bought it on ebay for $79 and its chrome to boot. You can find them almost anywhere. By going this route you have 1 wire that is routed to the battery side of your starter solenoid, and thats it. Theyre self exciting so they dont need an exterior 12v source from your ignition to operate. You can remove the regulator and the alternator/regulator wiring.
2nd Mustang
Founding Member
I'd start with the basics. First buy a reprint of the original factory shop manual, it's about $40 at most classic mustang stores. It has a trouble shooting section in it. Then buy a voltmeter, analog or digital, whatever you're comfortable with. With the engine running, CAREFULLY hold the positive lead of the voltmeter on the + terminal of the battery while holding the negative lead of the voltmeter to a ground source on the body. You should be reading 14 volts at idle. If you read less, then move the negative lead of the voltmeter to the negative post of the battery while still holding the positive lead of the voltmeter to the + side of the battery and see if you then see 14 volts at idle. Many electrical problems are just bad connections or worn battery cables. The battery cable could look perfectly good from the outside, but may not have enough capacity to carry the charge. Good luck.
TOM B
20+ Year Stangneter 
go back to bassics mxmattd. Is your glove box light on all the time. Look for the little things. I had about 7 mustangs in my time and just about all of them had a short in the wiring to the regulator, you know, the harness that gets routed under the radiator in the front rail, check it out. the guy that told you that you cant put a bigger amp alt in is full of it. I went with a power Master 100 amp 1 wire alt and it works great with the stock wiring.
You dont have dim headlights when you idle like with the stock alternator.
Mustang wiring is tricky, if the wired the radio to a what they thought was hot, like hooking it up to your coil resistance wire under the dash, you will have all kinds of problems.
You dont have dim headlights when you idle like with the stock alternator.
Mustang wiring is tricky, if the wired the radio to a what they thought was hot, like hooking it up to your coil resistance wire under the dash, you will have all kinds of problems.
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