1997 Legacy Computer Electrical Starting Problem

I have posted about this problem but have it narrowed down now and am doing my best to fix it without towing it to a Subaru dealership.

Here is what I have going on. The car only starts with certain steps taken but will not run very long. The battery is new, the alternator is bench tested and works fine. The starter works great.

It is very cold here and if I bring the batter inside and fully charge it and put it into the car, it starts up just fine. It will run for 20 minutes or so just fine if I have no heater or lights on, if I turn them on it dies pretty soon after and will not start again UNLESS I pull the negative battery cable off and put it back on but then is starts and runs poorly and dies and I might be able to start it again after disconnecting the battery cable but not always. I usually bring the battery in and recharge it and do the whole thing over again.

I assume the batter disconnect resets the computer. Is the alternator the cause of spark at the plugs or is the battery responsible for fire at the plugs?

I suspect I need to test somehow to see if the alternator is actually working in the car, not just the on the bench tester?

I would sure love to drive my AWD Sub some more this crazy record snow winter instead of gas guzzling chevy 454 truck.

Any ideas as to what I can do to solve this problem or narrow it down further?

Well the battery is only used to start the car and to cover any extra electrical draw beyond what the alternator is putting out. While the car is running, it SHOULD run entirely off the alternator. The thing to keep in mind is that the alternator only puts out a small amount of power at idle and low rpm, if the car doesn't want to run at lower than 2k rpm then I'd suspect you have a pretty major electrical draw somewhere. The cold could also be exacerbating issues but I'm not sure. When a acid cell battery drops below 32 degrees Fahrenheit, you lose half of the rated CCA. This is why on bitterly cold days, cars don't like to start, but it sounds like we can rule that out since you keep in indoors.

In order to help guide you in the right direction, to start off I'd pull off and clean all the electrical grounds you can find, most of the time, electrical issues are caused by bad grounds. If they all look good and the issue continues, I'd start pulling fuses for non necessary things to see if the issue changes, such as pull the fuse for the defrosters, 12v cig lighter, radio etc. If you were to pull lets say the blower motor fuse and the issue goes away, then that should answer where the extra draw is coming from.

I doubt this is it, but it won't hurt to put it out there.

I was having weird electrical once that indicated bad ground/ bad battery connects. My terminals were clean and looked fine but still the problem.

Turned out the positive battery cable was rotted where the terminal head connects to the cable. Simple fix.

So I guess I mean to say be mindful of what the electrons have to do, not just how the face of a ring connector looks clean. Look a little more and you'll find it.

I would venture to say to start the car with a full battery, pop the hood and disconnect your negative battery cable. If the car dies or runs like crap, the alternator is taking a crap.

This is an old school way of troubleshooting alternator/battery issues and normally I don't recommend it on newer cars because of computers, etc, but doing it once shouldn't cause any harm, because after all your symptoms point to the car is running completely off of battery power to begin with.

I would venture to say to start the car with a full battery, pop the hood and disconnect your negative battery cable. If the car dies or runs like crap, the alternator is taking a crap.

 

This is an old school way of troubleshooting alternator/battery issues and normally I don't recommend it on newer cars because of computers, etc, but doing it once shouldn't cause any harm, because after all your symptoms point to the car is running completely off of battery power to begin with.

I heard that used to work on all the older cars but I know a lot of new cars have a safety breaker to shut the car off if the neg is removed to avoid "damaging" electrical components. I don't know if that includes our old subarus though.

I heard that used to work on all the older cars but I know a lot of new cars have a safety breaker to shut the car off if the neg is removed to avoid "damaging" electrical components. I don't know if that includes our old subarus though.

That might be true because in a front end collision, the battery, if disconnected or damaged should have it's power cut to prevent fire or explosion. It might work on our older Subarus because I've seen people who have jumped 90's Subarus without a battery installed to test an engine. I haven't tried it, but I don't think the electronics are that advanced in our cars to warrant a safety trigger.

Another method is to hook up a voltmeter to the battery after you start it and look if there is parasitic drain to the battery with the engine running. If the alternator is running and working properly, the battery voltage should read between 12.5 to 14v. I thought my voltage regulator was going weak on my 99, but when I hooked up the voltmeter during running, the meter read a consistent 13.5v to 14v at idle. If the alternator isn't working, your voltage will continue to drop as it runs. When you rev the motor, it will also not show a drastic increase, if any at all.

I did have the alternator tested at Autozone and it tested fine. I plan to do what I can to see if there is an issue with the alternator cable and check the grounds and pull some fuses. We have sun today but a foot of snow all around my car. If we get our parking lot plowed today I will get right on this.

I truly do appreciate all the information and I sure hope I can get this bug worked out because I have over $4500 invested in this car and the only way to get that back is to drive for a few years. I just wish things like this would happen in the summer when I have 12 hours of day light.

Well, put the nice warm fully charge three week old battery in and it started right up but then I pulled the negative batter cable off and it died instantly. I put the cable back on and it started but ran like crap and died in about 10 seconds.

Now I am waiting to see if it will start again after things cool, but I suspect I will have to pull the batter out and fully charge again even though it only ran for 4 or 5 minutes before I disconnected the batter. I did have on suspicious fuse pulled to test it which I guess proves that is not the source of drain.

it will work on the 2nd gen because there is no ECU sense wire involved i think. ive used jumper cables to start my car with no battery to move it around the shop yard before. our alternators use two wires, one for the gauge (light) on the dash and one for a 12v signal to tell the regulator when it needs more voltage. the two are literally jumped in the harness, where the newer ones use the light, an actual signal as well as an input signal from the ECU to tell the regulator what to do.

i figured all this out when i put a 05+ outback h6 alt in my 95 wagon to get more amps out of it. the one i got was rated at 125A but the new ones are rated at 110A. either choice is better than our 85A alternators. the part number i used was 15718

it will work on the 2nd gen because there is no ECU sense wire involved i think. ive used jumper cables to start my car with no battery to move it around the shop yard before. our alternators use two wires, one for the gauge (light) on the dash and one for a 12v signal to tell the regulator when it needs more voltage. the two are literally jumped in the harness, where the newer ones use the light, an actual signal as well as an input signal from the ECU to tell the regulator what to do.

 

i figured all this out when i put a 05+ outback h6 alt in my 95 wagon to get more amps out of it. the one i got was rated at 125A but the new ones are rated at 110A. either choice is better than our 85A alternators. the part number i used was 15718

I'm not that qualified with a volt meter so I will have a buddy come help me. I will check the battery fully charge out of the car while it is nice and warm, check the battery while it is hooked up in the car, check the batter while it is running then when it dies I will take the battery out and check it again to see if it is drained.

I see my cooling fans connector is hanging low so I will also disconnect them before I start the car.

Also, and I know it is unlikely but the fellow who put my car back together used a spare bolt to put the alternator back in, it's too long leaving the alternator kind of lose. Is there any chance that the main alternator bolt is also a ground component?

yes, the alternator grounds through the brackets and engine.

when it dies, check it while it is still in the car first, any kind of draw goes away once you disconnect it.

if the cooling fans arent running when you turn the key to acc then they shouldnt cause any draw while starting the car.

yes, the alternator grounds through the brackets and engine.

 

when it dies, check it while it is still in the car first, any kind of draw goes away once you disconnect it.

 

if the cooling fans arent running when you turn the key to acc then they shouldnt cause any draw while starting the car.

WOW, I sure hope new hardware to secure the alternator in place is the problem. Obviously the tension bolt for the belt is fine but other other bolt is as lose as a goose. I'm not sure why it ran for 1 year and two months except maybe the extreme cold we are dealing with. Maybe I need to wire brush the points on the alternator and motor where the new bolt goes too.

Will find the right bolt and let you know. Thanks twisty!

Update, put the new bolt and bracket on but I am no longer getting spark even with a warm fully charged battery so now I can't get it started at all. Last time it started, I tried to drive it, it died and I haven't got it started since.

I tried starting fluid right into the intake and nothing. No spark at all.

What could have changed while working with that bracket? Is there a fault in the alternator harness that touches sometimes and after the work it isn't?

For a few months, I have always been able to start it with a warm fully charged battery that I keep indoors and place. However, the last time I started it I tried to drive it again. I've driven it before a mile round trip only to have it die soon there after in my parking lot, but the last time I zipped right out in traffic only to have it die with no shoulder to get out of way of traffic thanks to our record snow year. It hasn't started since then.

I was hoping I jostled the alternator from it's ground because it has been sloppy but now it is nice and secure and I did put a new clip on the alternator as well, it started after the new wire plug clip.

It still may be a lose ground some where. About two years ago I went 8 months without getting it started once and then one morning after an all night charge on the battery it started and I put a new battery in it and it ran for a year and two months and now I am back to where I was 2 years ago.

It turns over super strong and sounds normal just like it would at any proper starting. I replaced the coil, the ignitor, crank and cam sensors and I think the CEU two years ago without it starting.

WOW, I just got it started while writing this comment. I left the battery in after I tried starting it yesterday without luck and then I got in just a minute ago and the first crank made it sputter and the second crank started it. I have it running now and will see how long it runs.

Are we sure it's not a fuel issue? It's sounding more and more like bad fuel, water in the lines or a clogged filter

I did replace the fuel filter and the fuel pump the last time I had this issue to no avail.

This is what I believe is happening, I believe the battery isn't being charged by the alternator or for some reason the alternator is not powering the spark the way it should or both. It's frigid outside right now and I have my battery hooked up to a charger and sitting at about 76 degrees. I will put it back in the car in a bit and see if it starts today with the freshly charged warm battery. It usually does.

Water in the line, might be a concern as I haven't attempted that, if that is the case, I'm going to feel really stupid but excited at the same time.

Can you hear your injectors clicking as they open and close? You'd probably need an assisstant to crank for you. I would probably pull my plugs and put them back on the ends of the wires. Lay them on the block so they are grounded and watch for no spark. Be sure they aren't going to dump their 50kvolts into some wire or sensor. If you have no spark at some plugs look at your coil or maybe ignitor. If you have no spark at all pluga use a test light to check for correct pulses at the ignitor, but I would suspect crank position sensor or cam position sensor. These can be tested as well. I would expect crank sensor since it is under the alternator.

Also, have you checked for continuity in the big wire from the alternator to the battery even while flexing that wire? With good alternator and no charging that is one of the few items left regarding charging.

Can you hear your injectors clicking as they open and close? You'd probably need an assisstant to crank for you. I would probably pull my plugs and put them back on the ends of the wires. Lay them on the block so they are grounded and watch for no spark. Be sure they aren't going to dump their 50kvolts into some wire or sensor. If you have no spark at some plugs look at your coil or maybe ignitor. If you have no spark at all pluga use a test light to check for correct pulses at the ignitor, but I would suspect crank position sensor or cam position sensor. These can be tested as well. I would expect crank sensor since it is under the alternator.

 

Also, have you checked for continuity in the big wire from the alternator to the battery even while flexing that wire? With good alternator and no charging that is one of the few items left regarding charging.

I did replace the coil, the crank and cam sensor and ignitor a little over a year ago when I had the same problem that a brand new battery seemed to be the fix for a year and two months. I my crank sensor seems to be getting a considerable amount of power steering fluid on it making me a little suspicious of it. I'm just about ready to tow it to the sub dealer here to let them go through it, I fear they will charge me an arm and a leg for a simple fix I am not qualified to detect.

I think we are about to get a break in the weather next week, I will try to get a buddy here to help me do some of the diagnosing you suggest.

I know what you mean. I just did my A/C idler pully. First reasonable day in a few weeks when I was also not terribly ill.

But with the parts you've swapped vs. the weirdness of the problem I still feel like there is an intermittent wire or terminal rather than what we more traditionally think of as a 'bad part'. For the cam and crank sensors I expect it would be enough to take it off the car, connect a volt meter, and move a neodymium magnet past the can. If you get a little pulse of voltage it should be good. Clean any gunk and put it back.

I'd like to know what ohms are on the big wire from alternator to battery. You'd want to take out the battery for that test. And you'd want to check it slowly wiggling the wire to see if it is frayed internally. Better if you could do that test right after running the car until it died in case it only shows after loaded use.

Your car will run again. I just hope we can get through this sooner...