The car is a 2000 Nissan Sentra with a 1.8L four cylinder engine with 100,000 miles. This car seems to have many electrical gremlins, so many that I have decided to start with the battery/charging system. The owner has taken the car to many shops with no success. Things that have been replaced by other shops recently are:
1. Number 4 cylinder coil pack for misfire.
When the car was brought to me, it still had the number 4 cylinder misfire so I swapped the coil pack with the number 1, reset the codes and went for a test drive. The car had no power, engine began to misfire, hooked up my scanner and now it says cylinder number 3 misfire. I don't believe it is a bad coil, especially since I moved the one in question to cylinder 1 and a new misfire happened on 3. We kept driving it and the car turned into a dog, continuing to lose power to the point where I wasn't sure if we were going to make it back. It seemed like the alternator quit working and felt like the car was running off of only the battery.
We got back home, tested the voltage with engine running and yes the alternator wasn't charging. I turned the car off and checked all wires, did a battery check, starting system check, and alternator check (with my charging system tool) and all checked good. But, if you let the car run for a while the alternator will kick off, you can tell by the alternator getting quiet and a change in engine RPM, and then battery voltage slowly begins to drop.
2. Alternator was also changed recently.
When the alternator is running it puts out anywhere from 14.0 to 14.6 volts. Every time, as it runs for a while, the alternator turns off. I have noticed that if I wiggle the connector with the two control wires going to the alternator, sometimes it will cause it to turn off. Other times it just turns off (quits charging) on its own.
3. Battery is two years old but tested good.
The owner said this has been a problem even when she had the new battery put in, but now the electrical issues are getting worse.
Even when the alternator is putting out full power, the engine still seems to bog down and has a misfire. I realize that this is a very complicated question for a forum but I am just wondering if anyone knows of a common issue on this particular Nissan.
Tomorrow I am going to remove the battery and alternator to have them both bench tested.
Thank you all for your help, and thank you Scotty for your awesome videos, they have really helped me in the past and I know they will in the future. Also, thank you Scotty for personally answering two of my questions and one of them made it to one of your recent videos!!
You may have solved the problem. Don't ignore it.
The alternator's charging shouldn't be affected if you wiggle the wires or laterally push on the connector.
Maybe consider, either trying to make the female spade sockets in that alternator connector tighter (and cleaner if necessary), or just replace that connector.
Thank you for the boost of confidence. Even though the alternator was new, it failed the bench test. After removal, I found the compressor clutch power wire was pinched in between the belt tensioner bolt and the bracket, I assumed this happened when they installed the new alternator. I repaired the wire, rerouted it, wrapped it, and put the plastic auto conduit around it so that won't happen again.
The battery is good and the new alternator works like a dream. The car now works like advertised except for some engine hesitation, but that is for another post. As far as the electrical issues, the pinched wire repair and new alternator fixed this car.
Thank you.