1993 Nissan Sentra At my wits end with the car

ANDREWHART

MEMBER
1993 NISSAN SENTRA
6 CYL
2WD
AUTOMATIC
109,000 MILES

My car recently failed a Maine State Inspection because the brake and battery light came on and stayed on. Their diagnosis (which was confirmed by several other sources) was an alternator that was overcharging.

I changed the alternator about 3 weeks ago, and at first the lights didn't come on. Then, the past few weeks the lights would come on sporadically without any reason, and then shut off. You could hear the alternator kicking in and kicking out as the lights came in.

Last night the lights came on and stayed on, and the alternator won't provide a charge.

Earlier tonight I unplugged every wiring going into the alternator and unplugged the battery wires in the hope that it was a loose connection.
No such luck, and now I'm at my wits ends..

I've tried every connection available to me, starting from the 3 plugs that go into the alternator (a ground, a box-like plug in, and the wire that goes back to the battery). Those 3 wires run to another plug in, and then that plug splits into two cords that run into the engine area (and out of my view).

Do you have any possible ideas of what needs to be checked or changed?

9 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

I would be re checking the alternator and the voltage regulator, check that the battery is OK have it load tested, don't presume that because the alternator was replaced, it is not the problem.

Mark (mhpautos)

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Sunday, August 31st, 2008 AT 10:09 PM

ANDREWHART

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6 POSTS

I probably should have added this to the initial question, so I appologize.

When my car was initially diagnosed the problem was an alternator that was overcharging and a battery that was very low in capacity. So along with the alternator being changed I also changed the battery.

Can you explain where the voltage regulator is for a 93 Nissan Sentra?
I can follow directions pretty well (I have little car knowledge but I was able to change the alternator without a problem).

Also, does this possibly give you a clearer picture of the problems?
In the past few weeks since I changed the alternator I would notice the battery/brake light coming on intermittenly. When I say that, it would flicker and click for minutes at a time. The light would never really stay on, you'd just hear a "click-click-click. Click-click-click". Sometimes this would cease and the lights would be off, other times I'd reach my destination and shut the car off. And then upon returning and restarting the car the lights wouldn't be on.

I was thinking about changing the alternator again (it's got a limited lifetime warrantee when I purchased it from Autozone), but in your opinion would it be better to take it to a shop?

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Monday, September 1st, 2008 AT 6:03 AM

ANDREWHART

MEMBER
6 POSTS

I just got back from AutoZone, and had the battery tested. Unfortunately the guy who helped me didn't have ready access to a device that could test the alternator.

My battery is a bit on the smaller side, 540 amps.
After starting the car up and running the battery read 11.0 with a fluctuation of -.2 to -.3. Even when I held it at roughly 2000 rpm he didn't notice any difference in the battery, it still stayed within the 11.0 range.

Tomorrow when I get the alternator tested I'll provide more info.

Does this provide any additional help?

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Monday, September 1st, 2008 AT 4:07 PM

ANDREWHART

MEMBER
6 POSTS

Okay, after seeing a guy at Autozone (as my car sputtered and died... How lucky, huh?) I ran an idea by him. . . Someone at work said that maybe a fusible link had went. . . After checking the fusible links box located right next to the battery compartment everything seemed ship-shape. . . In my fusebox on the interior of the car I checked a fuse that's labeled as battery and it wasn't blown. . .

Okay, back to the alternator. . .

So he points out some black residue / powder located on the side of the belt for the alt. They line up with vent holes coming from the interior. I've included 3 pictures that I've taken of the alternator. I plan on swapping it out tomorrow for a new one and giving it a shot. If anyone has any suggestions, ideas, or advice I'm all ears!

This image is how it would sit in a car (bottom portion is the base), wire connections located on opposite side. Notice the black residue located down from the wheel. The camera I used isn't the best, but that material does go into those circular holes. None of this residue was observed on the wheel on the vent holes on the opposite side.

Having seen these three pictures, what advice is there to learn about this alternator? ... Do you think the alt is faulty? Is the residue evidence of a different problem? Is it time to put the car out to pasture?

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Tuesday, September 2nd, 2008 AT 7:48 PM

MHPAUTOS