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Hello Everyone!

I'm trying to help a friend diagnose and repair a problem with his 2007 Pathfinder LE and I'm hoping forum members can provide some insight. I'll be honest... I have worked on GM products almost exclusively but have a lot of experience with electrical and electronic systems in those vehicles. Nissan is definitely foreign to me, but since an electron is an electron (lol) I don't expect that solving this issue is unreasonable.

The problem is a 4.8A parasitic draw. Of course, this is enormous! I've been through some initial diagnostics and found no faults. I've measured current drop after pulling every fuse that we could find both under hood and in the dash. There was never any appreciable drop in draw. Of course the only fuses I was unable to pull were those in the large block that attaches to the battery post. I did however remove the two plugs that connect to the bottom of this block, and unless there is some other circuitry in this block, should have achieved the same result as pulling a physical fuse.

The only aftermarket device installed is the stereo. This was connected to the factory harness with an adapter cable, not hardwired to +12VDC and fused elsewhere. I confirmed by pulling the factory radio fuse which did cause the stereo to shut down.

I've read through two or three posts that suggest alternator failures can cause parasitic draw. I don't recall seeing anything to suggest this would explain such a large draw. As much as I'm not a fan of Alldata, we have subscribed to access factory schematics.

Can anyone offer further insight? Is there anyone else who has resolved such a large draw by simply replacing the alternator?

Thanks!
Darcy
 

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Ok, this is a long shot but it happened to me. You don't mention other symptoms so here goes.
I had an alternator power diode leakage problem that only could be found by pulling the power lead to alternator.

This was a suburban and started triggering an after market alarm when parked on a trip
Then on return journey the headlights dimmed. and since I figured we could make it home and it was in the middle severe storms we pushed on.

Next morning the battery was completely flat.
Took a while to find, new power diode assembly fixed it.
 

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Discussion Starter #4
Hey guys, thanks for the welcome and information.

There were in fact no other symptoms other than the battery constantly draining when not running. My friend took the alternator out and had a shop rebuild it. The regulator was visibly melted and I'm also told the stator pin was broken. As soon as the weather improves he'll reinstall it and we will test again for parasitic draw. I'll post an update as soon as I've got more information to share.
 

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The problem is a 4.8A parasitic draw. Of course, this is enormous! I've been through some initial diagnostics and found no faults. I've measured current drop after pulling every fuse that we could find both under hood and in the dash. There was never any appreciable drop in draw. Of course the only fuses I was unable to pull were those in the large block that attaches to the battery post. I did however remove the two plugs that connect to the bottom of this block, and unless there is some other circuitry in this block, should have achieved the same result as pulling a physical fuse.
There should not be more than a 50 milliamp draw on the system with the ignition switch in the "OFF" position. If there is a higher draw, you need to do some testing to find out where the draw is coming from. Remove fuses one at a time until the draw goes away or falls into acceptable range; next disconnect all the leads to the alternator; then start disconnecting the various harness connectors.

You said that the only aftermarket device installed is the stereo. This was connected to the factory harness with an adapter cable, not hardwired to +12VDC and fused elsewhere; maybe a bad adapter cable. Remove all connectors to the stereo. If all that you tried doesn't bring down the draw, then there's probably a short somewhere inside a harness. Whoever said that diagnosing a short was "a piece of cake".
 

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Hey guys, thanks for the welcome and information.

There were in fact no other symptoms other than the battery constantly draining when not running. My friend took the alternator out and had a shop rebuild it. The regulator was visibly melted and I'm also told the stator pin was broken. As soon as the weather improves he'll reinstall it and we will test again for parasitic draw. I'll post an update as soon as I've got more information to share.
can you ask if they checked the power diodes for leakage?
If the regulator shows signs of overheating that's probably it.
Good luck !
 

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I have had the exact same issues on a R51. Please search the posts and you will see my thread.

I did the same as the OP in that I removed ALL the fuses one by one.

I FOUND the fuses that had this horrible parasitic draw!

In the glovebox...remove the fuse cover and you will find that the fuse at the bottom left labelled KEY SW (for key switch), if removed, will drop the draw by about .42A...so most of the parasitic draw. I had to basically take this out every time I was going to leave the car for a few days...otherwise...totally flat battery!

I also found that the next fuse up - ROOM LAMP (the interior light circuit) was also drawing .8A...so I just kept that one out all the time!

So the mystery is...why is the KEY SW fuse/circuit drawing so much current when the ignition is off? I have heard, however, that this draw does drop after a while...but not enough to stop the battery dying.

It is possible that it might be a faulty diode in the alternator? Or maybe something else is using so much current when the car is off?

If you find out...please let me know!

TIP...when checking the amperage use...keep your multimeter attached for a little while (maybe 30 seconds) until it stabilizes...otherwise you will get a false reading.

I suspect that this is yet another issue with these cars that Nissan has failed to own up to...or is hoping it will go away....if you check all the Nissan forums...this is incredibly common!

Best of luck!!
 
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