Battery draining 89 LX Mustang

Alot · Oct 11, 2018

Car has been sitting under a cover. Started right up but the next day the battery was dead. Charged it up but it did it again. I bought a new battery and after sitting a few days dead again. Charged it up. I know very little about cars but looked on Youtube (Thanks EricTheCarGuy) and set up my multimeter to the neg cable and neg battery terminal. It showed 3.5 amps. I only found the one fuse box to the left of the drivers seat and pulled out each of the fuses one by one but nothing changed. No visor, dome or hood light was on. If I let the dome light on it would go to around 4. So compared to that somethings really putting a load on. Is that all the fuses I can check? Any suggestion for what someone with my basic level can try further are appreciated. Thanks

General karthief · Oct 11, 2018

Long shot here, it needs to be dark, in a garage or cover the car with a blanket, look for a light on in the instrument panel, glove box, rear hatch/trunk light. also try, Hook up your vom like the car guy showed and unplug the alternator wiring. see if the drain goes away.i
have you installed any aftermarket electronics?

mikestang63 · Oct 11, 2018

start disconnecting one wire from the solenoid at time and see which circuit it is on. Could be a bad alternator or wiring. Did you do a voltage drop test along the primary circuit .

Alot · Oct 11, 2018

General karthief said:
Long shot here, it needs to be dark, in a garage or cover the car with a blanket, look for a light on in the instrument panel, glove box, rear hatch/trunk light. also try, Hook up your vom like the car guy showed and unplug the alternator wiring. see if the drain goes away.i
have you installed any aftermarket electronics?

Thanks for this and Mikestangs reply. No aftermarket electronics.Everythings oem as far as I know. This is a hatchback. Is there a rear or trunk light? When I lift the hatch I know the main dome light comes on (but it's not on when the hatch is closed). Is there a physical switch for the hood light like what the door and hatchback have? I couldn't see anything in the hood area. I did unplug the hood light just to see but still 3.5 amps being drawn out. I'll have to study up on how to remove the wires from the alternator and solenoid. First I've got to find them (that shows my level!). But I think I'm up to try that. I disconnected the battery and covered the car as some rain is expected the next days but will check it in darkness when the front is past. Would lights like that be drawing that many amps? For what it's worth, two electric related things I noticed when I was driving the car around for the 1st time in quite a while. When I put the new battery in, the dash battery gauge wasn't as high as I expected. Also the dial that controls the dash lighting and dome light wouldn't do anything at first but after moving it around some times started to work.

General karthief · Oct 12, 2018

The underhood light has what I think is called a mercury switch, as the hood is lifted contact is made and the light comes on. Like horizontal is off, vertical is on thing.
at the back of the stang, where the latch bolt is there is a hatch light, you should have a plunger switch that activates it. Mine is white and deteriorated so I un pluged it damn! I forgot about that, something else I gotta add to the growing list of things to fix!
somewhere around here is a post on how to find a battery drain, open circuit, that is very user friendly, I'll try to find it, meanwhile get yourself a repair manual since you are kinda green at this automotive repair thing, I think I got mine from motorbooks,

Mustang5L5 · Oct 12, 2018

Normal draw when at rest should be pretty low. Under 1/4 AMP or so and that's usually voltage the radio or any security systems uses to store the stations and stay passive.

If pulling fuses doesn't relieve the car of that 3.5A draw, you'll need to investigate the wiring on the starter solenoid. Disconnect them all and do the same thing checking with your meter in series.

My guess, it's the silver circuit breaker on the solenoid that has the drain.

Alot · Oct 12, 2018

General karthief said:
The underhood light has what I think is called a mercury switch, as the hood is lifted contact is made and the light comes on. Like horizontal is off, vertical is on thing.
at the back of the stang, where the latch bolt is there is a hatch light, you should have a plunger switch that activates it. Mine is white and deteriorated so I un pluged it damn! I forgot about that, something else I gotta add to the growing list of things to fix!
somewhere around here is a post on how to find a battery drain, open circuit, that is very user friendly, I'll try to find it, meanwhile get yourself a repair manual since you are kinda green at this automotive repair thing, I think I got mine from motorbooks,

Left to me by deceased relative a long time ago. It just sits except for a few times a year when relatives come and I drive it around so they can have the other car. I mentioned above that everythings original except I forgot I changed the lights to more modern looking ones when one got broken.If that might have any connection. So there is a light in the hatchback area near the back latch? I'll have a second look. Never noticed it. The plunger switch there turns on the dome light in the front. If I take the bulb out of the hood light could it still be drawing power? Thanks for the info!

Alot · Oct 12, 2018

Mustang5L5 said:
Normal draw when at rest should be pretty low. Under 1/4 AMP or so and that's usually voltage the radio or any security systems uses to store the stations and stay passive.

If pulling fuses doesn't relieve the car of that 3.5A draw, you'll need to investigate the wiring on the starter solenoid. Disconnect them all and do the same thing checking with your meter in series.

My guess, it's the silver circuit breaker on the solenoid that has the drain.

Appreciate your comment. I'm going to try that next. By the way is it just a matter of releasing a lock on the wire with a screwdriver to get it loose or do I unscrew the nuts on the solenoid to release the wires? Thanks

General karthief · Oct 13, 2018

If you took the hood light bulb out there will be no draw

Mustang5L5 · Oct 13, 2018

Visor lights are another common source of drain

Alot · Oct 14, 2018

Mustang5L5 said:
Visor lights are another common source of drain

Thanks. Checked the visor lights. Actually taped them down some years ago when the felt around the cover started getting weak and turning them on. Going to check that solenoid when the rain quits.

Mstng93SSP · Oct 15, 2018

I have had two alternators in the past that drained my battery. Try unhooking the alternator and see if you still have a draw.

wiseguyk · Oct 15, 2018

Looking forward to what you find as the culprit. I've got some kind of parasitic drain happening as well but haven't gotten around to troubleshooting yet like you are

89ripper · Oct 17, 2018

These draws can be a lot of fun to find. Visor light was my culprit

StratTone · Oct 17, 2018

Sounds like you are on the right track and have been given good advice. I also agree that if you did the parasitic draw test as per Eric the Car Guy and pulled all the fuses with no changes I'd suspect the alternator however as mentioned the starter might be a good place to look as well. Another clue is to feel the alternator and starter with our hand. Usually they will feel warm to the touch if they are drawing power.

Boostedpimp · Oct 17, 2018

Recently I found my wiper motor to be a constantly draw and actually getting warm to the touch for no reason. I disconnected for the time being because I'm currently troubleshooting a fuel issue with the car but worth a look.

General karthief · Oct 17, 2018

That constant draw from the wiper motor will drain a fuel tank in no time.

Boostedpimp · Oct 22, 2018

General karthief said:
That constant draw from the wiper motor will drain a fuel tank in no time.

Hey if the wiper motor was the reason for the fuel pressure drop I'd be happy

Alot · Dec 29, 2018

The car has been covered and just got uncovered. I left the battery on overnight and sure enough the alternator was warm. I had auto zone run their test and they said some diodes were out so it failed one part of the 2 part test. Got a replacement and this morning it was nice and cool and the battery was 12.5 instead of 11.5 after sitting one night. Thanks a lot for all the replies. A big help!

StratTone · Dec 30, 2018

Good deal! Glad you're back up and running!

Battery draining 89 LX Mustang

Alot

Member

General karthief

wonder how much it would cost to ship you a pair

mikestang63

Alot

Member

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

Alot

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Alot

Member

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

Alot

Member

Mstng93SSP

You have a nice rear end there Dave.

wiseguyk

89ripper

StratTone

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Boostedpimp

General karthief

wonder how much it would cost to ship you a pair

Boostedpimp

Alot

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StratTone

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