alternator not charging battery
 

I have an 88 civic ( automatic sedan ) A while back the alternator light came on. I replaced the alternator thinking that was the problem, well a few days later the light is on again. It seems to only come on just when I start the car and will go off about 15 minutes after driving. WHile the light is on my headlights are dim and the heater fan almost non-existant ( so I drive without the heater, to conserve power) After about 15minutes the light goes off, and my headlights are back to normal.

The wiring connections at the alternator are tight and clean.

Any suggestions. I have swapped number 14 fuse and it does not solve the problem. I can not locate number 31 fuse under the hood ( not sure which it is ) but I am guessing that if it was a fuse then the light would never go out.

Anys suggestions? Is there a relay or voltage regulator that I should be checking?

I would hate to have to bring it in to a shop, as it is so unpredictable and intermittent...problems one day, then no problems for two days, etc. Any help is appreciated...thanks in advance.

Your new alternator could be a dud. The voltage regulator is inside the alternator. Also test the "I" wire at the alternator, I think it is black and yellow, it should have power when the key is on. If not there's a problem with the fuse under the dash or the wiring. Test for continuity from the big output terminal to battery (+), that goes through the underhood fuse box (the two big white wires).

thanks mk378, I think I have it narrowed down, but now I am stuck. I found a pdf that shows how to test the charging system in this vehicle and it passes all the tests but for one.

With the green plastic fitting removed from the alternator and the key in the on position (engine off) by putting a test light on the L fitting (White/blue) the test light does not come on so I am to check the Wht/Blue wire from alternator to charge warning light, and also to check the Blk/Yel wire from dash fuse box to charge warning light.

Any idea as to how to check these, and better yet, how to get to and find these. There is so little room under the dash, and I have no idea.


Here is a link to the pdf, #5 is what has not passed. http://www.pprok.com/pi0036.pdf

I could not load the pdf, will try again later.

The black and yellow wire is powered from the fuse under the dash, it should have power all the time the key is on.

The white and blue wire operates the battery warning light. If you ground the white and blue wire and turn the key on, the light should come on. That seems to be working anyway since you have had the light come on.

The big output wire goes back to the battery through a main fuse. You should have battery voltage there all the time. While replacing the alternator be sure to disconnect the battery because the big wire is live all the time and if you short it to ground, the fuse will blow.

If all of those are OK I really think the problem is the alternator itself. Take it off the car and back to the store and have them test it.

Test of fuse 14 and the Blk/Yel wire:

With the key turned to ON(II) (engine off), use your test light to check for voltage at both small metal test tabs located on top of fuse 14 while it is installed in the fuse box. You should detect voltage at both tabs if fuse 14 is good and the Blk/Yel wire is good.

Also move to Test 6. Do you measure voltage at the Blk/Yel wire terminal (IG)?

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Sorry, but I am a rookie,I may need some help here, do I attach the one end of the test light to ground, and then place the test light pointer onto each side while the fuse is still plugged in? I'm not at home right now...will there be room, or do I take the fuse out and test at the fuse 'recepticle'? I assume that there is supposed to be power on one of those two points (or both points if fuse is installed.)

Test 6 was good, the test light did light up, so I assume that the fuse is alright.

The small plastic car fuses have metal test points on the top of the fuse that you can probe while it is still plugged in. Really it sounds like the rest of your car is OK and the problem is the "new" alternator.

If test 6 gives voltage whereas test 5 does not, then there may be a problem with one of the two sections of the Wht/Blu wire, the Blk/Yel wire between the cluster and dash fuse box, or the dash fuse box itself. You can check these components with a combination of continuity and voltage tests.

wella sincere thanks so much everyone. Your help was much appreciated, and I did learn a bunch but I ended up taking it to a mechanic this evening before they closed, as I would not feel confident if I had to in fact replace some wiring underneath. I let the mechanic know what I had tested, in hopes that the labour is less, if he can find the culprit right off.

I will let you know how it works out, in hopes that maybe it helps someone else some day.

For the record, I'm betting on the yellow/blk, but then I wasn't aware you could check for voltage with a fuse still inserted:)

bing, bing bing! mk378, it looks like you were right. The mechanic said that there was voltage at step 5 on the L wire, but it would not light his test light either. I couldn't believe it. So the test was actually passed. SO now it is time to replace it again. He figures maybe one of the brushes is bad, and that is why it was intermittent.

Does anyone know of an easy way to get the alternator out. I don't want to have to remove the axel. The last time, as I am not sure I have all the right tools or confidence for that. Last time I ended up stuffing the alternator up and across the back of the engine, but it is a tight fit, and I feel that one of these times I will damage a hose that is back there as it is a very tight squeeze to get it by, but it is the only way I could get it out, and the new one back in.

I know it will not come through the top and can't seem to get it out of the bottom.

It's a tight fit any way you do it, reportedly it is simplest to remove like you did-- bring it over to the right side of the car (near the starter) and lift out.

The failure of the test light to turn on in test 5 whereas it did in test 6 suggests a problem in the L circuit to me. If you repeat test 5 but instead ground the L terminal to the engine or frame with a jumper wire, does the dash battery/charge system warming light turn on?

The alternator drops down and out from below after the mount bracket is removed.

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Well as it turned out the test 5 was actually passed (I wasn't too clear in my last post) The L did not light my test light or the mechanics, but the mechanics voltage meter showed voltage...I can't remember what it was. I had to see it with my own eyes. The mechanic mentioned something about bulb impedance of our test lights...I thought it was odd that it would not even glow, yet there was voltage showing on the test meter.

Anyway I took it back (they bench tested it and found it to be faulty as well so they exchanged it)

I did however find an easy way of removal and reinstallation. (88 civic automatic sedan 1.5L)

I drove it up on car ramps, and removed the plastic shroud near the drivers side front wheel, and both the alternator and the lower mounting bracket. There was not yet enough room to get it out, so I raised the drivers side of the car a wee bit to take the weight off the wheel. With the wheel essentially lowered a bit, in relation to the body the alternator then easily came through between the wheel-well and the steering part that was orginally stopping it. ( Whatever the part is that was stopping it was now lowered allowing a larger opening between body and it)

Because my car was on car-ramps I had to set the jack on a couple of blocks and had to lift further down from where the proper lift point is.) I blocked that side of the car and only put my arm underneath to slide the new alternator back through, and then removed the blocking and jack before crawling under to continue the installation.

If I have to do it again I will use jack stands, and then it should be a fairly easy job.

Thanks again everyone, I really do appreciate you taking the time to share your knowledge.