87 hatch ea81, When Im driving at low speeds, my battery light is very dim, and will get brighter, and my lights will dim as well, and then get brighter when i step on the gas, and the battery light will go off when accel, or just reving up. I changed my belt, because the old one was a little loose and old. What do you think it could be? Alternator? or battery?

i am betting grounds.clean every possible thing that is related to grounding.

i would also start by running the engine at operating temp to check the alternator output with a voltmeter.

 

when you rev it up to about 2500 you should see a significant change to about 14.4v?(please correct me if i am wrong.)

 

but , i would start with grounding her better.....you know.teach her some yoga or something:grin:....

cheers, b

Alternator should put out 14.4v at an idle. If you wanted to try the ground trick... easy way is to just take a part of jumper cables from your alternator/bracket to the negitive post on the battery. Could also take those same jumper cables and hook them to the positive side of the battery to the charging post of the alternator. That would eliminate a broken or corroded charging wire. Also look at your fusable link, I have one go out on me the other day and it did some goofy stuff... Just my .02... hope it helps

I checked grounds all tight.. new terminals, .Still doing it. I dont have a voltmeter which sucks. But Ill try that next. Its doing it less now for some reason, on the way homoe the light came on like 5 times. But on the way to work it went on liek 50 times.. So wierd

I would suggest you look at either a new/reconditioned alternator or work out how to pull the one you've got apart and replace the bushes in it.

 

There would be plenty of options for upgrades available if you need a bigger alternator.

 

Cheers

 

Bennie

Yeah Im going to buy a nissan maxima alternator for sure.

I was having the same issues and am on my third cheap reconditioned alt in about 2 months and the volt meter reads ok when no light,heater rear defrost, or anything is on but when I run all three of these at idle im in the low red. It runs and starts fine but if u get a new alt try to get a good one, or a maxima alt which by the way what years and does it just bolt n hook right up? GL with your issue. Sorry I cant help more.

Im not familiar with Subarus of that era, but I have dealt with lots of other aged electrical issues. My first guess would be the regulator, since the battery light sometimes come on from overcharging the battery, and if it's stuck open, it can damage the battery and the alternator, and cause funky electrical issues (including fires).

 

First step in diagnosing any electrical problem is changing the alternator and regulator. Its cheap, easy to change, and if it doesn't fix the problem, you can clean it up and return it to the store!

 

Get one with a warranty, you'll be here thanking me in a year or so

I was having the same issues and am on my third cheap reconditioned alt in about 2 months and the volt meter reads ok when no light,heater rear defrost, or anything is on but when I run all three of these at idle im in the low red. It runs and starts fine but if u get a new alt try to get a good one, or a maxima alt which by the way what years and does it just bolt n hook right up? GL with your issue. Sorry I cant help more.

 

Another thing you want to watch, and this may or may not be true for you, is that the battery is the right size, and that the terminals don't touch the hood when its down. Another issue I had with charging was when my hood prop-rod worked its way over to the alternator connector (since the clip to hold it is broken) and literally exploded. Thankfully my main 100A fuse went before the truck did :-\ Not that this happened to you, but these are the kinds of problems you should be looking around your car for.

Edited March 3, 201115 yr by cj7135
typo

Before you purchase anything I suggest you have a load test done on the charging system. The results of that will tell you the condition of things and show you what needs to be done to correct the problem. You may need to get both a new alternator and a battery. If the battery is more than a few years old and you install a new alternator it would be wise to replace the battery also to help prevent any further trouble in the near future.

 

There could also be other issues going on here, like a bad connection between the battery and the alternator output. The load test should check that possibility out.