98 frontier charging problem

[cheapspeed]

I have been on the forums for a long time now but rarely post. My truck has presented a problem we cant seem to find. The alternator went out a few months back I replaced it with an aftermarket one that obviously didn't work. Had the factory one rebuilt still didnt work. Replaced a third time with oem and it worked for three months replaced again with oem under warranty. Now it charges solid at idle and driving intermittently sometimes 14.2 give or take. If you put a load on the system headlights blower motor etc. it gets a normal voltage drop but does not return once they're turned off. Checked the alternator fuse its fine as well as the rest of the system so far. A friend checked the bulletins on it said there is a resistor in the ecu or main relay that can cause this but i cant get ahold of him to find the bulletin number. Nissan says they dont have a bulletin showing this to be true. In searching the forums i found a mention of the battery idiot light bulb burning out causing problems. But this was on a q-series car not a frontier altough i assume the charging systems are similar. The truck has a alpine head unit but no fancy system just alpine type r's. Only other electrical system change is an aftermarket harness for a trailer. No Cel's no batt light no brake light when it starts to die out the abs light comes on the passenger air bag off light comes on and it gets ignition break up obviously. Also the gauge cluster resistor is bad so the gauges dont work but seems to be unrelated because they have been like this since i got this truck two years ago. Any thoughts would be appreciated I am running out of ideas. Thanks in advance, Manuel

[Desert Rat]

Sadly, it still sounds like an alternator issue to me. Dealerships even sell remanufactured ones these days. Is there any way you can try another one?

What condition are your battery cables in? If there's corrosion at either end it could be keeping you from getting a full charge.