Dear Scotty,
I was going to try and see you in Middle Tennessee, but since you moved I guess I have to email you.
I have a 2015 Nissan Quest SV about 142,000 miles. In Spring of 2021, the battery and brake light came on the dash. My husband changed out the alternator and the battery with new products. The charge was too high. We took it to a mechanic and they changed out the alternator with new products too. They cannot get the dash lights (brake and battery) off and the charge I still too high. (16.something) We have been researching for a solution, but we cannot find an answer. Everyone says to change the alternator and battery which we did. We have still been driving it but…now we are having codes concerning o2 sensors having high voltage, but we cannot find the problem. When the o2 sensor trips a code, the minivan starts bogging and having a hard time driving. It starts jerking. This month we changed out all the coil packs and the spark plugs. I am uncertain about changing out the o2 sensors because I still have high voltage readings. Can you please help me figure out the high voltage issue, so I can fix it?
P.S. We have checked fuses and fuse links too.
Thank you for any help you can provide me, Scotty.
Betty from West Tennessee
I definitely agree with getting the voltage issue sorted out. The voltage regulator on those alternators is internal so you could be getting unlucky bad alternators back to back(I have seen that before) otherwise the electrical connector going to the alternator I’ve seen melt or corrode causing poor pin fit which will also cause some funky concerns . As long as those brake and battery lights are on you definitely have a charging system problem.
Betty,
I think you need to focus on the voltage issue. I would stop changing out sensors and random things until you get the charging sorted. The codes could be a result of the voltage issue.
This job will require (A) knowledge of how the charging system works and technical references like electrical schematics and (B) some amount of troubleshooting and computer diagnosing to isolate the issue and (C) the proper tools.
It's not something I can perform over the internet I'm afraid, so please see a professional.
Otherwise you'll be changing parts until the cows come home, have no solution, and an empty wallet.
