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[hairhook]

Greetings,

[hairhook]

I have a 1991 N/A that the charging lite came on today. I checked across the battery with the engine off and got 12.2 VDC. With the engine running it reads 14.40 VDC. It happened all of the sudden since it has been running well for the last four years, Any ideas?

[Rocketman]

How old is the battery? 12.2V is a little on the low side at rest, should be 12.6ish
 14.4 is correct for running

Charge light on is generally indicative of a bad alternator, can you remove it and bring it to have it tested somewhere?

[hairhook]

I checked the battery voltage today and it reads 12.4 volts with the engine off as to 14.4 volts running. I can't decipher the wiring for the charging circuit, but if the alternator is bad, wouldn't the battery voltage be the same running or off?

[greywolf27030]

I checked the battery voltage today and it reads 12.4 volts with the engine off as to 14.4 volts running. I can't decipher the wiring for the charging circuit, but if the alternator is bad, wouldn't the battery voltage be the same running or off?

yes

[GermanXR2]

I have the same problem:

Batterie full
Motor runs
Voltage at Battery 14.4V

Battery control light: ON

 

[greywolf27030]

Does the battery voltage drop off after sitting a few days?

[hairhook]

I went out yesterday to close the windows on the car and when I started it, the charging light didn't come on anymore. I checked the voltage across the battery with the car running and it's 14.4 volts. I have no Idea how the damn thing fixed itself!

[greywolf27030]

I went out yesterday to close the windows on the car and when I started it, the charging light didn't come on anymore. I checked the voltage across the battery with the car running and it's 14.4 volts. I have no Idea how the damn thing fixed itself!

It may have just been a failure iin the regulator that sent a signal to the bulb but didn't affect the charging.

[EShepherd]

I went out yesterday to close the windows on the car and when I started it, the charging light didn't come on anymore. I checked the voltage across the battery with the car running and it's 14.4 volts. I have no Idea how the damn thing fixed itself!

It may have just been a failure iin the regulator that sent a signal to the bulb but didn't affect the charging.

So I don't know how much this information will help anyone, but I suspect Wolf might have the right idea. So I work for Nissan, and that's actually the most common way for our alternators to fail. They will work perfectly (as far as charging the vehicle), but something internally will fail, triggering the idiot light on the dash. If you are seeing more than 14.2v at the battery with the engine running, I'd say you're probably in good shape.