# Over charge problem



## Jetster (Jan 23, 2016)

Just bought a used 2001 Sentra 1.8. After a week battery light came on and then battery was dead. Replaced battery with a new one I had. Checked volts with a fluke after start. 18 v. So its charging all the time. Pulled the two small wires off. I guess being the warning light and sensor wire. Still charging wide open. 18v. Any Idea? I don't just want to replace the Alt. and then find out its something else. It also has a check engine light. O2 sensor. 

Thanks


----------



## jdg (Aug 27, 2009)

First question would be which Autozone reman alternator did you buy?


----------



## rogoman (Dec 16, 2004)

Jetster said:


> Just bought a used 2001 Sentra 1.8. After a week battery light came on and then battery was dead. Replaced battery with a new one I had. Checked volts with a fluke after start. 18 v. So its charging all the time. Pulled the two small wires off. I guess being the warning light and sensor wire. Still charging wide open. 18v. Any Idea? I don't just want to replace the Alt. and then find out its something else. It also has a check engine light. O2 sensor. Thanks


A properly working charging system puts out about 13.2 to 15.0 volts. If the warning lamp does illuminate, then check to make sure the circuit between the battery positive post, or fusible link, to the connection in back of the alternator is good. On Nissans, this will be a thick (approx. 10 gauge) white wire to the "BAT" post on the back of the alternator. It's not uncommon for this wire to get corroded and burn up, creating resistance in the circuit. So, before assuming an alternator is bad, make sure this circuit is good and battery voltage is getting to the alternator. When a charging system is not charging, or overcharging, a lot of "strange" things can occur. It's not uncommon to see a multiple of stored trouble codes in the ECM memory. So, whenever a car is setting a multiple of trouble codes, idling funny or stalling, or anything out of the "norm," test the charging system before you start pulling hairs!


----------

