[89 5.0 LX]

Hello all, I have a '89 5.0 hatchback that somehow drains the battery after only a few days.

It began a few weeks ago when the battery was completely dead (radio clock reset) and I had to push start it to get from my dorm to auto zone. The alternator was only putting out 11.8 Volts, so I bought a brand new one and put it in myself. It was charging correctly (around 14.2 volts) after that, so I drove it to charge the battery.

I parked it again for a few days then as I went to drive it the battery was dead. (radio clock reset) The battery showed 9 volts with a handheld voltmeter. I took the battery out of the car and charged it. When it was fully charged I put it back in the car, and it wouldnt even turn the starter. I thought it could be a bad battery (it was 3 years old) so I push started it and drove it to wal mart to get a new battery. They said that it was good, but I bought a new one anyways.

I parked the car for a few more days and yet again when I tried to start it, it slowly turned over and barely started.

I drove it from college back home (about 200 miles) and a mechanic relative and I went through the electrical system. Replaced the ignition switch module, as the old one was coming apart, then used a test light between the battery cable and the battery. (it lit up) Took fuses out one by one and replaced them to try to find one that killed the light. None did. Then we looked at the A/C? relay on the passenger side fender. It was warm. There is a red wire on the connector that the relay plugs into that showed 12 V with the ignition off. Dont know if it should be powered all the time or not..?

Im back at school now and I disconnected the battery cable when I parked it today. The only things I know of that draw power constantly on the car is the (factory) alarm and the clock on the (factory) radio. I have had this car for a while and have not had any problem with it losing power before. I have no idea what could be using power still, much less use enough to kill a new battery in 2 days. Has anyone heard of anything like this?

Thanks in advance for any help!

[Tony_90fox]

hey man, there are about three people (including me) who have had battery problems in the past few days just on this site. After i jumped my car, a guy came up to me and asked to jump his car too, so my uncle did that. I bought a new battery, and it is alot better but man, make sure not to leave anything on. I think my sun visor light was on for four days while i was at college. i dont drive much here so i never get in my car. good luck man, i dont know what the problems are all of a sudden with these batteries. LOL

[87foxbodylx]

also, if the new battery doesn't work, try looking if there is anything taping into the battery and if there is get a disconnection switch for it. if all else fails just get a new alternator good luck.

[Twist 2 Go]

disconnect the neg battery cable and put a test light between the cable and the battery terminal. If it lights up, you have a draw. Since this pretty much started after the alt replacement, disconnect the voltage regulator and see if the draw goes away. The cheap alternators from a-z and advance are prone for that.

[89 5.0 LX]

Originally Posted by Twist 2 Go disconnect the neg battery cable and put a test light between the cable and the battery terminal. If it lights up, you have a draw.

Thats one thing that my relative did. I took out all the fuses one by one and replaced them, but no matter what fuse I took out, the light didnt dim.

Originally Posted by Twist 2 Go Since this pretty much started after the alt replacement, disconnect the voltage regulator and see if the draw goes away. The cheap alternators from a-z and advance are prone for that.

I havent tried this yet but it sounds very possible. It will be the next thing I try. Do these alternators have built in regulators or is it external somewhere?

[Twist 2 Go]

they have a built in regulator. It's the small 3 pin connector on the alternator. One thing to remeber also, is that not everything on the car goes through the interior fuse panel but through the fusible links at the fender mounted starter solenoid.

[89 5.0 LX]

Well I disconnected the negative cable and put a voltmeter in between the negative post on the batt and the negative batt cable while the positive cable was connected. It shows 13 volts. (I guess I could be just measuring the voltage of the batt by doing this??) Then I unplugged the small 3 pin plug on the alternator and no change. So I guess I will have to go through the fusible links on the solenoid one by one.

[Twist 2 Go]

don't use a voltmeter, use a test light

[1gunner23]

i don't think voltage is what you want to look at. try looking at amps. DCV is across B+ to B-, your amperage is in line. you should only have about .25 amps draw or less if i remember right. and start pulling fuses till your reading drops, but this is just me.

[Mustang8719]

Originally Posted by 1gunner23 i don't think voltage is what you want to look at. try looking at amps. DCV is across B+ to B-, your amperage is in line. you should only have about .25 amps draw or less if i remember right. and start pulling fuses till your reading drops, but this is just me.

+1
Hook up to the battetry and terminal like this.

And make sure you measure amps.
About .25 or less is normal.

[89 5.0 LX]

I have traced the draw to a fuse link wire on the solenoid on the fender. It is a blue 20 gauge fuse link wire. I disconnected the neg. cable from the batt and put a test light between the cable and the post, then took the wires off the solenoid one by one, leaving the red (battery cable) and the blue wire (it was under the others). It is the only thing that illuminates the test light. (very bright) The blue wire then turns to fuse link and enters the wiring harness, then dissappears.

[Mustang8719]

http://www.veryuseful.com/mustang/tech/engine/
Check out this site and try to figure out where the wire leads to from the wiring diagram on the site.

[89 5.0 LX]

Thanks for the site, according to the main harness diagram, the wire goes to the computer, and is probably the power source for it. That makes sense, because when I touch it to the hot post on the solenoid, a few things click on and off and I can hear the fuel pump cycle. Probably the computer going through its "checklist" or what have you. I hope its not the computer crapping out. Almost seems unlikely; everything seems to be functioning properly.

Another thing I checked was the AC relay on the passenger side fender. It is always warm, and it always has power to it as long as that blue wire is connected to the solenoid. I tried taking the relay off to see if it was draining the power, but it wasn't. Yet I am not sure if it should always have power to it even if the ignition is off and the AC switch is off.

[Mustang8719]

One of the links or the power source that feeds that wire is bad.
When you go to the soleniod you are always giving it power.
Something switches it on with the key.

[89 5.0 LX]

The only thing I can think that would be bad, according to the color diagram would be the EEC power relay.

It hardly seems likely because I would think that when a relay goes out, it will NOT let power through, even when the ignition is on.

It has crossed my mind that it could be the ignition switch, but I have lately replaced that, thinking it could be the problem.

Is it possible that the relay could have stayed on, always powering everything connected to it, even with the ignition off? The only reason I think this possible is the fact that the A/C relay on the passenger side fender, now has power ALL THE TIME, even with the ignition off, granted the small 20 gauge blue fuse link wire is powered.

Another thing that confuses me, is that when I power the blue 20 gauge fuse link, I can hear various relays switching on and above all, I hear the FUEL PUMP. According to one diagram, the fuel pump is on the same fuse link. On another diagram, its on a different fuse link, one that is not powered when I power the blue 20 gauge fuse link wire. From what I gather, the fuel pump relay is good; the car won't run without it.

[Mustang8719]

I had my fuel pump relay stick on a couple of times and power everything you say is powered.

Also do you have anything aftermarket tapped into any wires?

[89 5.0 LX]

I found out what was wrong! It was the EEC relay that is just above the computer, under the passenger side kick panel.. As I was taking it out, every time I would tap it with a screwdriver, the fuel pump would run. It seems that the relay somehow welded itself shut, as to always allow power thru.

Thanks everyone for helping me with this problem! Please take note for future reference; I know I will!

[Tony_90fox]

glad you found the problem.

[Mustang8719]

Congrats glad you found the bad relay.

[1gunner23]

nice work man! congrats