Odd electrical issue

[dougkehl]

Hey everyone, first post here on this forum.

Recently (Wednesday) I encountered an issue with my 2002 Pathfinder, and it's a strange one. While driving the car two days ago I turned the headlights on and the car immediately shut off and lost probably 75% of the electrical capacity that should be going through everything from the battery, but the battery still had over 12 volts and around 14 prior to it shutting off last I checked it.

What's really got me stumped is the car maintains a lack of electricity anywhere past the battery. Most of the dash lights are dim, or start bright then flicker and mostly go out, the gas gauge wont even read, an no accessories will work except the dome light which goes dim if I turn the key. If I put jumper cables on it in an attempt to give it an extra bump it will do the same thing and then all of a sudden everything gets power and it fires right up and stays running until you either turn it off or attempt to turn the lights on. Yesterday I messed around with it and got it fired up and I drove it from my house to my fathers house which is a 300 mile drive one way and it was fine the whole way and now it's back to not starting.

So far all I have verified is that all power and ground connections coming from the battery are good and I've removed all headlight fuses and relays to see if that would make a difference seeing how turning them on will immediately kill the car.

This car sat in my dad's backyard for about 3 years until about a month ago when I pulled it out and went through it so I could drive it again, so I have not ruled out that a mouse may have caused some damage to the wiring and it finally showed it's face. Other than that I'm not sure what to think besides the ignition switch being crappy.

Any input about where to start or things to check is appreciated!

[yeldogt]

sounds like alternator.

Was the car outside ? they have a rust recall .. FYI

[dougkehl]

It was outside and the alternator was seized when I began working on it, but I broke it free and it's been working fine since with charging, but I'm not sure why I didn't think of that because my good friend had a 2000 GTI that also had this similar issue and the alternator had shorted out pretty bad.

I'll have to check it out.

[dougkehl]

Okay here is what I found, first the negative battery cable was loose on the terminal, but this has made no difference now that it is tight. The alternator appears to be good as I did get it running after about 30 minutes of fussing around with it, and it showed a solid 14 volts and no current draw while the car was not running. Also, even if it was bad how would it prevent the car from turning over if the battery has 12.5 volts which is more than enough to start the car?

Now that it is turned off it is doing the same thing as mentioned in the original post. I decided to check and see if I was getting 12 volts to the ignition switch, which I am.. Some of the time. Here is how I determined this:

1. Prior to turning the key to start I measure the voltage which reads 12.47 at the power feed for the ignition switch.
2. I turn the key in an attempt to start, but nothing more than a few clicks from relays under the dash occur.
3. I quickly measure the voltage at the power feed for the ignition switch and I get anywhere between 6 and 8 volts and then a faint click happens within about 5 -7 seconds of turning the key back to the off position which appears to be coming directly from the ECU. Once this click occurs the voltage immediately spikes back up to 12.47 volts.

So is the issue with the ECU possibly? Could the loose negative battery cable have shorted something out inside the ECU? It appears as though I have over 12 volts everywhere until the key is turned.

[dougkehl]

3. I quickly measure the voltage at the power feed for the ignition switch and I get anywhere between 6 and 8 volts and then a faint click happens within about 5 -7 seconds of turning the key back to the off position which appears to be coming directly from the ECU. Once this click occurs the voltage immediately spikes back up to 12.47 volts.

*Edit* it was not the ECU that was clicking it was the SEC box that makes the faint click.

Also the voltage just went from 12.47 volts with the key off to 5.05 volts with the key in the crank position and then upon putting the key back to the off position voltage only made it to 11.2 volts and then dropped to 7.3 volts all with the battery still maintaining 12.5ish volts the whole time.

[Rockwood]

I had a very similar experience on my QX4. In my case, it was the red connector on the positive battery terminal that was corroded internally.

There are two 8 gauge wires that run over to the underhood fusebox coming off of the connector. They can be removed by stripping the wire loom back a little, and pressing down on top of a tab on each wire where it inserts into the connector. Check for corrosion.

In my case the wire closest to the positive terminal was so corroded it could not be removed. The connector is not available as a separate part - so you have to rig something up or visit the junkyard for a used one.

Just like your experience, I turned on the bright lights one night and the car died. Took me a while to find that - but the car has been fine since.