Hello,
I have been having an issue with my headlight flashing when I decrease speed and as I'm braking to stop or turn. I researched and figured it was the alternator going bad since I have 108 K miles. I replaced the battery about 3 month ago as well and cleaned the terminals really good with baking soda so that should be ok.

I deciced to take to the dealer to have it checked out. The hooked it up and did a system check and said the alternator was fine but said the belt tensioner was going bad because there was too much play in the belt and it was slipping on the alternator. So I had the tensioner and belt replaced.

few days later while driving at night the same issue happening so scheduled 2nd appointment.

I guess we will see what they come up with this time. Any ideas?

Thanks

bobbel0809 wrote:Hello,
I have been having an issue with my headlight flashing when I decrease speed and as I'm braking to stop or turn. I researched and figured it was the alternator going bad since I have 108 K miles. I replaced the battery about 3 month ago as well and cleaned the terminals really good with baking soda so that should be ok.

I deciced to take to the dealer to have it checked out. The hooked it up and did a system check and said the alternator was fine but said the belt tensioner was going bad because there was too much play in the belt and it was slipping on the alternator. So I had the tensioner and belt replaced.

few days later while driving at night the same issue happening so scheduled 2nd appointment.

I guess we will see what they come up with this time. Any ideas?

Thanks

no, but I'd like to know the underlying cause when you find out.
was the new alternator aftermarket? rebuilt? new OEM?

Thanks eieio for your reply.

Sorry i wasn't clear on the alternator part. I assumed this was the problem going into the dealership but they said it was fine and didn't need to be replaced. We will see what happens when I take it back in this week.

bobbel0809 wrote:Thanks eieio for your reply.

Sorry i wasn't clear on the alternator part. I assumed this was the problem going into the dealership but they said it was fine and didn't need to be replaced. We will see what happens when I take it back in this week.

your symptoms sound like an alternator/voltage regulator, or battery related problem.
the regulator is part of the alternator.
that's why I asked about the source of the replacement alternator.
when you say that the headlights "flash", do you mean go dim when the brake lights are on, or flicker, or?
do the headlights do that without applying the brakes at all, as in at low RPM while coasting?
do you have any kind of harness connected to the brake lights? trailer wiring?

The alternator is the orginal one that came with my 2011 SV V6 because I bought it used with aboout 42K miles on it and haven't replaced it.

The lights do more of a flicker like you said. They dim down for about 1/2 sec right at the end of braking when the RPM of the engine go down.

One other thing I forgot to mention was the light sometimes would do the same thing when I used the turn signal and the switch came back to the home spot and I would get that short dimming down. That issue has been happening for a few years so not sure if they are related.

I do not have any type of harness for the trailer hitch

I have an inexpensive tool that comes in handy. It's a voltmeter that plugs into the power socket (cigarette lighter socket), so you can monitor your voltage while you are driving. Charging system voltage should be 13.2 volts to 15.5 volts, at idle and at 3000 RPM with and without loads "on" (loads=lights, heater, radio, etc.). I've had a couple of cases (not in an R51, however) where the regulator was bad but not detected in the shop, but started overcharging while driving, causing the vehicle electronics to "freak out." You can get them in the automotive section of places like Walmart and at many auto parts stores and they're under $20:

https://www.walmart.com/ip/Equus-Innova ... r/15137663

Thank you for the information on this voltmeter. I looked it up on Amazon and looks to be about the same price.

I was thinking about something today because I always keep my phone charger plugged into the top power port so was going to see if having something plugged in or not will make a difference with the dimming.

Thanks again!

I purchased the volt meter you sent me the link on and seems to be working good. I get green lights during driving with about 14.5 Volts.

When my Pathfinder is off I get yellow and red lights so thinking it could be something with the battery. Wondering if during the time I purchased the new battery and before I had the belt and tesioner replaced if the battery was damaged from the slipping belt.

I'm currently sitting in the waiting room at the Nissan Dealership so we will see what they come up with.

I dunno if this may help, but some times the negatives can cause issues like this. Trailer lights are the worse ! We've all seen it, following someone towing and they indicate and the lights flicker and they brake and the turn lights glow, again usually the connector earth.

Try disconnecting the battery and giving all the earths a good clean, battery connector and where the earth strops go to the engine and body. Over time the threads corrode and insulate. Ive even changed the bolts for shiny new ones in the past to get a decent earth.

Maybe worth a try?

The result from taking it back to the dealership was nothing but at least it didn't cost me anymore. Thanks for the advise on the earth ground and I will look into that. Are there any other ground location besides the opposite end of the battery cable to the frame?

It is interesting that you mentioned the earth ground because I disconnected the negative terminal to clean the connectors for the front lights with CRC QD Electronic Cleaner because I was worried that maybe the connections to the front lights was dirty. I thought about maybe replacing the low/high bulbs to see if maybe there is something going on there.

This leads into a 2nd issue with just the clock time not holding the correct time after I reset it. Each time I have disconnected the negative terminal to work on my SV and then hooked back up and reset the time will not hold after turning Pathfinder off. Once I turn the ignition off and turn back on after about a minute the clock resets. I was able to fix this a few weeks ago by spraying the same CRC cleaner on the key and quickly inserting it to clean back and forth and turning it to clean the terminal. so this worked to help the time stay until i disconnected as per about to clean the front light connectors so I'm resetting the clock each time to start my SV.

Thanks