Battery keeps draining - short somewhere? HELP

[ACVWguy]

Alright, everybody - first time poster, two year lurker here.

It's a pity that my first post isn't an introduction to me and my car, but actually a rather desperate problem that needs fixing fast. Anyways... my battery keeps draining. I know there's a short, I just can't figure out where.

I'll try to provide as much information as I can, from the day the problem began.

I have a 1991 Legacy wagon 5-speed 4WD with 249000 miles. I bought it 2 years ago with 214000.

I replaced the alternator and battery a year ago.

I replaced the oxygen sensor last summer (universal 3-wire type spliced in).

I pulled the transmission and replaced the clutch 3 weeks ago.

Now,

For the two weeks after I replaced the clutch on my car, I had no electrical problems whatsoever (or any problems with the car for that matter). Last weekend, I went out to start my car - put the key in the ignition, clutch to the floor, turned the key and... no dice. No click, no dash lights, no nothing. The battery was drained. I used my mom's Outback to give it a jump-start. I hooked up the jumpers to both cars, turned on the Outback, then hopped inside the Legacy to give it a start. I pushed in the clutch and turned the key... all the dash lights turned on and the car started without a hitch. So I figured all was well, and I hopped outside and pulled off the jumper cables.

As soon as I pulled the jumper cables, the engine started stumbling and lugging itself, the windshield wipers turned on, the headlights burnt out, the radio went haywire, and a puff of electrical smoke came out of the dashboard in front of the passenger seat. I immediately turned off the car and unplugged the battery. I looked around the engine bay and found that I had broken the ground strap on the transmission when I changed out the clutch. I made a new ground strap and installed it. I then checked all of the fuses in the fuse box under the dash and the one in the engine bay... all where fine - none cooked. I jump started the car again, fired it up and unhooked the cables. The car ran just like normal. I hopped inside again and checked to make sure everything worked. All the switches and idiot lights worked, but the headlights were burnt out, and the radio display was shot (stock radio) - it still lit up, but it looked like an lcd screen that was left out in the sun. The radio still played, the buttons all worked, but the display didn't.

I went and bought some new headlights and installed them. I drove around town a bit, came home, and didn't start the car until the next day.

I went out to start the car this morning, and no dice... again. No dash lights, no solenoid click, no nothing. So, I unhooked the positive battery terminal, pulled out the ohmmeter and measured the resistance across the positive cable and ground cable with the battery out of the circuit. The resistance was 3.9 ohms - so there's a short. I held the leads on the ohmmeter against the positive and ground cables, while pulling fuses out of both fuse boxes trying to isolate the shorted circuit. The only fuse in either fuse box that increased the resistance when pulled was the "clock/room" fuse. When I pulled that fuse, the resistance increased to 30 ohms. 12v/30ohms=0.4 amps. There is still 0.4 amps of draw so my battery still drains, just slower now.

I checked every fuse, every switch on the dash, unplugged headlights, etc. and no other circuit would increase the resistance and expose another short...

Where should I check next? My battery will be dead by tomorrow morning and I have work - this is my only car.

Help please!

[Falken-18c]

i have similar problem i think its could be my radio but i sugest when your done drive disconect the batery til you find the problem

[vrg3]

With the missing ground strap, the alternator's charge current had to find another route to ground. The voltage drop across that poor ground could have tricked the alternator's voltage regulator into producing a higher voltage, and the overvoltage would have cooked the headlight bulbs and some of the radio circuitry.

Measuring the resistance between the terminals in the absence of the battery isn't a reliable way of determining how much current is being drawn with the battery hooked up, because the car's circuits aren't purely resistive. The usual way to measure parasitic load if you don't have an ammeter is to use a shunt. Put a piece of stainless steel (I've used a kitchen knife) in series with the battery (disconnect one of the terminals and put the piece of stainless in between the terminal and the post) and measure the voltage across it. Then remove the stainless and measure its resistance, and then use V=IR to infer the current.

You may well find that without the "clock/room" fuse the parasitic load disappears. Doesn't that fuse feed the constant-power circuit of the radio? I bet the radio is your culprit.

Until you figure it out for sure, Falken-18c's advice is good -- for a couple months I used to drive around with a sticking ignition relay. I kept one of these on my keychain.

[Legacy777]

Check all the grounds. The tranny ground really shouldn't be a big deal if the other grounds are good. So check the ground on the starter, the body ground, and you may want to add an additional ground between the negative battery terminal and the sensor ground spot on the intake manifold.

[Bender-san]

Are you familiar with a parasitic draw test? If so, do one now. If not, find someone who is and have them do one. All it takes is a 0-10A ammeter.

[ACVWguy]

Alright, sorry everybody for the delay, but I got it fixed.

My dad and I got the wiring diagrams off of this site:
http://www.main.experiencetherave.com/s ... FSM_Scans/

I had to drive my mom's Outback to work for a week during the day (she worked nights) because I was too busy to fix the Legacy. Anyways, I had to drive the Legacy last week so I just brought a crescent wrench everywhere and disconnected the battery whenever I knew I wouldn't be starting the car for a few hours. The battery had 12 amps being drawn from it somewhere, so the battery would die in under 4 hours. Well, last Thursday, when I got home from work, I pulled into the driveway and the car started to smell of burning oil (and my car doesn't burn any oil), so I got out and looked under the hood. There was oil all over the transmission and the rear of the engine... and there was a good 5 inch puddle of oil under the car. There was oil seeping between the engine and transmission and it was fresh. Only one possible leak... the rear main seal. I had replaced it when I replaced the clutch but I forgot to put oil on it... so it wore out in a few miles. ( ) Damn it. I had to remove the transmission AGAIN.

So last night my dad bought a transmission jack (we rented one last time) and we popped out the transmission in a few hours and pulled out the seal (which was dripping fresh oil).
Today, we put in the new seal (after soaking it with fresh motor oil) and using a real seal installer tool. While pulling the transmission, we found that one of the CV boots was shot and all 3 others weren't going to last much longer. We bought one piece CV boot kits (I don't trust split boot kits) and tried to disassemble the joint but it wouldn't budge. The we figured we'd replace both front halfshafts because they were only $53 at Autozone (lifetime) and four new boots would cost $60 anyways, not to mention we had a hell of a time trying to install them. So we put in the new seal, inspected the recent clutch (not even fully broken in), and installed the new axles, put it all together and decided to trouble shoot the electrical. This time around, I remembered the transmission ground strap.

So here's what we did (well, my dad did most of it because electricity is his specialty). He got out the ammeter and the wiring diagram, pulled all of the fuses one by one and put them back in... nothing would drop the load. So he looked at the wiring diagram and found that the interior fuse box couldn't be the source of the fault. He followed the diagram and found that the positive cable from the alternator was drawing a load. As it turns out, the alternator had a direct short (shorted stator) that was constantly draining the battery at 12 amps (also, with the engine running, it was putting out 17 volts to the battery). I think that the lack of a transmission ground strap may have caused it, but it's just a hunch. Anyways, I had replaced the alternator last winter when it gave out with an Autozone lifetime alternator. So we just took it back to Autozone, they tested it and it failed as soon as the tester turned on. Every time for three tests. So we gave them the phone number that the warranty was on (I have a good memory) and we were out of there with a free alternator! With the new alternator installed, the short was solved and the car runs great!

We also took this opportunity to replace all of the brittle PCV hoses and fittings with new ones. And we bought a new three wire NTK made in Japan O2 sensor for only $18 shipped and installed it as well. No more CEL!

So, I'm a happy camper. Now, I just need a new radio...

[Bender-san]

When purchasing an aftermarket head unit, be aware of the radio issue discussed in multiple areas, but lastly here:

http://bbs.legacycentral.org/viewtopic.php?f=19&t=48743