I started my Pathfinder up the other day and noticed that my transmition light, battery light and brake light all came on at the same time. Nothing seemed different about how the car drove and there were no awkward sounds. I came home and did some research on-line. It doesn't seem to be my alternator because I still have power. Has anyone every had this problem? Any suggestions?

2001 Nissan Pathfinder LE 4x4, 100K miles.

Thanks!!!!

Battery and brake are tied together by 2 diodes and then tied to the AT temp fluid, a combination that can be energized by a single fault issue by the alternator.

The battery light generally lights when current is reversed, the brake light works via low brake fluid and parking brake applied.

To have all 3 at the same time is a possibility. but not probable.

As an educated guess the problem may be stemming from your alternator, why? The diodes are not affected by DC but by AC and the alternator could be failing or leaking with an AC ripple into the DC via the rectifier built in.

Examine the alternator connections and test the output. A good multimeter can indicate the AC ripple or a failed or failing diode within the rectifier.

In the mean time disconnect the battery + and - leads, verify the - is having a good ground connection, then verify the + lead is not having a reading. It must be oV with battery disconnected, no voltage from the alternator.

After about 15 minutes and tested good, connect the battery. If your battery is 13 V or lower charge it with an independent charger to float voltage, then hook it back up.

With a charged battery, start the vehicle, then listen to the alternator, a meter on the terminals of the battery on DC should read from 13-15 V, no higher, try reading the voltage on AC, should get nothing, but if something the alternator needs examining.

Listening to the alternator you are listening for a high pitch frequency that should not be there since you have charged the battery, if there, the alternator needs work.

If when running you are much higher than 15 V the regulator is shot, but it could be a failing rectifier causing it.

Check the alternator fuse - it should be an 7.5 amp fuse. It is located in the fuse box next to the battery.

I have the EXACT same problem. I checked my alternator fuse and it is good. That alternator looks like a b**** to get at... probably easiest from underneath?

I had the similar problem in my Frontier. I changed the Ignition Switch. That solved the problem.
The ignition switch has normally two parts. The front part where the key goes in, and the back part where the electronic/mechanical part goes.
see the pictures:
https://www.japanesetruckdismantling.ne ... -ea00a.htm

https://shop.advanceautoparts.com/p/int ... ion+switch

This is the part that I changed and solved my problem with the dash lights. They were on all the time.
Now is working great.

winnipegjohnston wrote: ↑

Fri Feb 03, 2012 6:55 pm

I have the EXACT same problem. I checked my alternator fuse and it is good. That alternator looks like a b**** to get at... probably easiest from underneath?

If you have the 3.5L and RWD then it's not too bad of a job. Took me 3 hours to change mine out.

3-hours-to-replace-an-alternator-t618487.html