Subaru brat charging problem

[AKIRA]

My 84 brat has a problem, when I start it up, the "stop lamp" "brake fluid" and "parking brake" lights on the dash all stay lit (even with the e-brake off, no foot on the brakes, the fluid level is fine), along with the battery voltage being low enough to have the warning light come on. each time I started it the volts dropped and it got harder to start.

 

right now its at 10 or 11 volts, but I had the battery on a charger for an hour or two, before I did it was at 8 and it barely started.

 

I tested the voltage after I charged it, its the same with the engine off and when the engine is running, the book I have says I should take it to the dealer or a reputable garage because there is a problem with the charging system.

 

It did this same thing about a year ago, but when I replaced the alternator it stopped, but its come back and no alternator will make it go away. I have replaced both the battery and alt. with the ones form my loyale and it still does it. when I had the problem this time, it fulctuated a few times, going from normal to lit up and back. now its just staying lit up.

 

so its not the battery or the alt, what should I start checking, and how? the manual just says to take it to the garage. is it in the wiring?, and how do I check that?

[RavenTBK]

Well, when those three lights come on together with the engine running, it means just that.. your alty is kaput.

 

Are you 100% sure you've got a good alternator?

 

Are you 100% sure you replaced all the blown fusible links from your last *cough* error?

 

Check that the T plug is firmly seated in your alternator.

 

Pull the T plug, grab a test light, turn the key on, and make sure that the large diameter wire produces 12v with the key "on".

 

Take your multimeter and verify that theres battery voltage present at the B+ stud on the alternator (engine off pls). Dont disconnect it (and start a fire this time ), just probe it.

 

And.. uhm.. thats all I can think of right this moment. If it fails the above, we can dig deeper.

[AKIRA]

checked the links, the plug, its all good. your two tests came up good too.

 

It probabaly is just a bad alternator. It was just weird that the remanufactured alt that I replaced the old one with went bad too, and the one from the loyale is bad as well, when it was working just fine before I parked it. coincidence?

 

can I test the alt. to see if it is bad using my multimeter?

[edrach]

The three lights coming on usually indicate that the diode trio in the alternator have failed (not the main diodes that supply the current output). Sometimes you just have to chalk this type of failure to bad luck. However, I once had a battery with an intermittent internal open (not short) that caused two good alternators to fail (sorry I can't remember if it was the diode trio that went out or just no output). This can happen inadvertantly if you disconnect the battery while the car is running; or if there is a really bad connection at one of the battery terminals or at the other end of both ground and positive wires. Make sure everything is tight and clean.

[critical_max]

I concur, I had to retighten connections at the back of my alternator a month after installing it because the output bolt's nut came loose. Double and triple-check that stuff. Make sure your battery cables/posts are clean. Is there any corrosion or such on anything? Test all the wires with a low ohms setting with your multimeter, end to end to make sure resistance is low.

 

Also, how are your grounds? Another thing for the multimeter. Make sure you have good ground from block > unibody. This is the sort of thing I checked when working this problem out, anyway. Good luck!

[AKIRA]

I replaced the alternator, its not that, still does it with the new one.

 

so I will start testing the resistance of wires.

[AKIRA]

I tested these:

from neg terninal to unibody, block, alt body

from the + post on the alt to the fusible link

the large wire on the plug to the fusible link

other side of fusible link to pos batt terminal

 

all of them read less than .5 ohms of resistance

 

and the battery is at 12.5 volts, yet it reads just into the red on the dash guage

 

and yes, I disconnected the battery before I did the resistance measurements

 

what else should I measure?

[gbrand]

I had a similat problem on my 80 wagon. Every once in a while all my dash lights would come on, and on that car the engine would die due to the alt output being used as a "kill switch" for the fuel pump.(I had rigged up an overide switch to keep the car running because of a previous problem) Anyway I found wiggling the "T" connector on the back of the alt would fix it-could actually hear the engine speed decrease as the load from the alt engaged. Spray out with contact cleaner, bend the prongs or replace connector if this is the case-it drove me nuts but I think I solved as I found the same connector in my junk and spliced it in to the wire harness.

 

Not sure if your problem, but wiggle the crap out of it with the engine running and see if it makes a differnece

 

let us know how you make out

[AKIRA]

I don't have a cleaner, but there is no corrosion on the contacts, I did bend them in so the connection is very tight now, but no amount of wiggling made a difference.

[AKIRA]

bump? we are stumped on our end.

[Cougar]

Lets do some live tests to see if we can find out what is happening here. From your post #7 it sounds like there is a problem with the wiring between the battery and the cars main power buss.

 

With the car running and the RPM's at around 2,000, turn on the headlights and set the blower to high. Measure the voltage between engine ground and each of the wires on the alternator. You should see over 12 volts on each of the wires. Check the grounding by moving the common meter lead between the engine ground and the negative battery post (not the cable clamp). You shouldn't see any change in voltage from the first reading. Another way to check this is to place your probes on the alternator output lead and the positive battery post. You should see very little voltage drop across the leads. Checking the ground is done the same way by placing the leads on the engine ground and the negative battery post. You should see very little voltage drop.

 

If things are ok there then we need to check the voltage getting to the main fuse panel. Place the red meter probe on one of the main fuses and the common to chassis ground. You should see about the same voltage you saw at the battery, at least 12 volts. If you don't, then check the chassis ground by placing the probes between the negative battery lead and chassis ground. If the ground is ok, there should be very little voltage drop. Then place the leads between the positive battery post and one of the fuses in the panel. If you have more than a couple tenths of a volt drop then you need to track the wiring between the battery and the fuse panel for a connection problem. Most suspected areas are the battery connection and the fusible links.

[AKIRA]

Just checked, I found a problem:

I got 11.99 volts from the large post on the alt to the neg. terminal

12.06 on the large wire in the plug

66.7 mv! on the smaller wire in the plug

 

from neg terminal to engine ground I got 2.6 mv

from the large post on the alt to pos terminal I got 286.6mv

[Cougar]

Ok, good job.

 

The lead that had the 66mv on it is your problem. One thing to check is the warning light for the charging system. Does it light up when you turn the key to the run position but not starting the car? If it doesn't then that most likely is the problem. The light may be burned out. The light is in the alternator exciter circuit and if there is no voltage to the exciter then the alternator will not produce any output.

 

If the light is ok then you need check the wire connections.

[AKIRA]

you mean the red light by the voltmeter right? yes it is lit up when the car is "on" but not running.

 

news, when I tried the fuse test with my dad, when he stuck the probe in one of the fuses, it was reading about 11.7 volts, but then the car suddenly started idling a little lower, the lights disapeared and it jumped up to a little over 13 volts. we weren't able to reproduce this but by pushing on the fuse box we can make the "wrong" dash lights dim slightly. tomorrow I will pull the panel off and try to find a connection that is loose or a wire that is not conducting.

[Cougar]

Great. It appears you have a loose connection somewhere.

[AKIRA]

no amount of jiggeling now will get the lights to even flicker, its some fluke that made it work that one time.

 

I took my lower dash off, and I was able to get a good continuity from the WR wire from the alt to where it hooks to the "charge" 10A fuse. it becomes a brown wire from there and then dissapears up into the dash.

 

so I am sure that the wire is good up to the fuse.

 

I am tracing the wiring from the diargam in a haynes manual, trying to get to a point that I can access without tearing the dash appart.

[Cougar]

You didn't state if the alternator is putting out the 13 volts still or if it went back to the none charging mode. Does the fuse have 12 volts on it?

[AKIRA]

sorry, forgot to mention that. yes it went back to the non-charging mode, it only worked for a few seconds - and I have not been able to recreate it.

 

not sure if the fuse has 12v on it, I was checking continuity with the continuity setting on my meter (it gives resistance and beeps if there is a connection)

 

I'll check to find the voltage on the fuse

[Cougar]

Checking for voltage at various points while the problem is happening should be able to lead you to the problem fairly quick.

[Cougar]

I thought I would check my '88 manual to see how things are wired and it looks close or the same as yours. The WR wire from the alternator goes to fuse #9 and then becomes a Brown wire going to the 'Charge' warning light. On the other side of the light connection the wire becomes a Blk/White wire that ties to a connector and then becomes a Red/Yellow wire that ties to fuse #12. Your problem may be with the wire between fuse #12 (if yours is the same) and the charge lamp.

[AKIRA]

from the "charge" fuse to the negative battery terminal is getting 5 volts?

yet the wire has less than one ohm of resistance

 

the one beside it is getting 11.5 v

 

oh and I'll sheck the #12 fuse to charge lamp wire too.

[Cougar]

Is your 'charge fuse' fuse number 9? Just curious to know if it is the same number as mine is.

 

The 5 volts you saw is probably being backfed from the alternator. That wire appears to be ok. It is the wiring between fuse #12, through the lamp and to fuse #9 that may be the problem. The exciter power is supposed to come from fuse #12, through the charge lamp, then through fuse #9, and then to the alternators' WR wire. At least if your wiring is the same as my manual shows it to be for an '88 model GL.

[AKIRA]

what is the #12 fuse called? my wiring diagram shows a wire leaving the charge light and going straight to a 15A fuse, but it does not identify it beyond that. there are no red/yellow wires going to the fuse box

[AKIRA]

Is your 'charge fuse' fuse number 9? Just curious to know if it is the same number as mine is.

 

The 5 volts you saw is probably being backfed from the alternator. That wire appears to be ok. It is the wiring between fuse #12, through the lamp and to fuse #9 that may be the problem. The exciter power is supposed to come from fuse #12, through the charge lamp, then through fuse #9, and then to the alternators' WR wire. At least if your wiring is the same as my manual shows it to be for an '88 model GL.

 

I don't know, my diagram does't label the fuses at all. it just shows tyhe wires going to them, and what amperage rating they are, I only knew that the charge fuse was what it was because of the labeling in the fuse box, and the wr wire went to it.

 

and I can't identify it from where it is in the box, the "charge" is in a different location in the diagram than in my car

[Cougar]

Well it appears there are some differences then.

 

"my wiring diagram shows a wire leaving the charge light and going straight to a 15A fuse"

 

Does the diagram show where the other side of the fuse goes? The power side of it.

 

"What is the #12 fuse called?"

 

The fuse supplies power to many control circuits for relays and warning lights.

 

One thing you might try is to check the voltage of all the fuses and see if you can find any more with less than 12 volts on them with the car running or the ignition on at least.