Alternator problems-Infiniti G20



My son has had the alternator replaced twice at a well know national car parts and repair chain. Battery light is still coming on. It is a new battery also, and new belt.


Some more info would help. Were these 2 alternators back to back replacements with no month in between etc.?
Did the vehicle appear to be fine at first with no battery light on?

I do not have a wiring schematic for this car (unknown year of course) but most Nissan based vehicles have always used a fusible link, or two, between the alternator and battery.
If one of those links is burnt into or has a burnt/corroded end it’s possible that any charging current from the alternator cannot reach the battery and this leads to premature alterantor failure.
The alternator MUST have a load (the battery) on it.

It’s also possible that he could have gotten 2 bad alternators, but that’s stretching a bit.
One would hope they’re doing an electrical system test not only before the diagnosis, but also afterwards.


Thanks very much for the reply. It is a 98 Infiniti G20; here are some other details which may or may not be relevant.

  1. “Wiring harness” for signal lights replaced by dealership two weeks ago

  2. Three days after, battery light comes on, my son then replaced the battery, not knowing that it was a charging system problem.

  3. Of course this did not solve the problem. Battery light stays on.

  4. Takes it to dealer who wants to replace alternator and belt and power steering belt for $800. Sticker shock sends him to the car parts store.

  5. First of two alternators put in and new belt. First belt was very noisy, they then adjusted it.

  6. Same day car dies on the interstate, at night. Very scary.

  7. Second alternator installed under warranty. Battery light comes back on same day it was installed.


It sounds like there may be a problem in the car wiring that is causing the trouble, like OK4450 mentioned. The problem could cause the alternator to produce full output all the time and kill the alternator after some period.

I don’t blame your son for having sticker shock. The dealer would have most likely installed a new alternator and they can be very expensive. I recommend he take the car to a shop that specializes in electrical problems and have them install the replacement alternator. They should be able to find the real trouble for a reasonable repair cost.

One thing that may be causing the trouble is a poor connection from the battery to the alternator as OK4450 said. It could be in the alternator output line or the battery voltage sense lead for the regulator. The alternator’s regulator needs to see what the battery voltage is to keep the charging at the correct level. If there is a poor connection causing a voltage drop in the line then the regulator will make the output current go higher to compensate for the low voltage. This makes the alternator work more than it should and can cause an early failure. A good shop should be able to find and fix the trouble within an hour.


That info puts a different light on it.

So why was the harness changed? There should be no reason to unless it was suspected there was a short in the wiring. Was this the case?

I’m afraid I can’t be much help on this one except to recommend checking fuse links or fusible links, whichever it has, between the alternator and battery or there is a wire harness problem causing a short. If a short were the case one would think a fuse would pop first before knocking out an alternator.