Electrical Gremlin

[pathfinder2001_green]

New poster in desperate need of assistance.

The situation: 2001 Nissan Pathfinder LE (used w/ 150k miles). Purchased recently for my son. Car died on him ~2 weeks ago while driving (headlights worked but no auro windows, door locks, etc., had to use the shift release to get it into neutral so we could tow it home). Identified a blown 40A IGN fuse in fuse box next to battery, Replaced fuse and as soon as the key goes from the OFF position to the ACC position the fuse blows. I have looked for shorts but have not found any so far. Just asking for a T/S procedure to identify where the issue exists, e.g., relays, alternator, starter, battery, etc. What should the voltage/amperage be across that fuse? Can I safely put some heavy gage wire across the terminals to measure the amperage?

Thanks for any help!

[Blindaviator]

ACC powers so many things it will be tough to find. But if the 40a fuse is blowing but none of the others do then it is going to be a big short such as the alternator or starter, something that can draw a LOT of power quickly...

If it was me I would pop the hood and disconnect every single electrical connection. Get under it and disconnect everything you can find... Then I would pull every fuse and relay under the hood and under the dash... Disconnect EVERYTHING you can find that would draw power... Then drop a new fuse in it and turn the key... If it blows then you have eliminated about 90% of the car... If it doesn't then leave the key on and start putting the fuses / relays back in one at a time until the fuse blows...

Make sure you record what size fuse / relay goes where... Take pics with your phone beforehand just in case...

[pathfinder2001_green]

Disconnected every fuse/relay (except battery) in the engine compartment - plan to do passenger compartment next. Had battery tested - good. Still blows fuse.

Thinking bad starter solenoid at the moment. Will try to pull starter when heat wave blows over. That's the only other thing I can think of that would generate that much amperage.

[Blindaviator]

If you still have the stock battery cables then you should be able to disconnect the starter power wire but still apply power to the accessory wire... The 2 main acc wires can be unplugged from the main wire as they are basically plugs... Then you could make up a jumper wire to connect each one separately to test... That would be much easier than removing the starter to test...

Just as a note you can unplug the wire powering the starter solenoid without removing the starter... About 4 inches from the starter the solenoid wire plugs into the body side of the wire... If you can get your hand in there you can disconnect it...

[Blindaviator]

Thinking bad starter solenoid at the moment. Will try to pull starter when heat wave blows over. That's the only other thing I can think of that would generate that much amperage.

The alternator could be shorted inside pulling a lot of current... But there is a 120a fuse by the battery that may be for the alternator (haven't looked at wiring diagrams to see)...

[pathfinder2001_green]

As for the alternator, I did disconnect the alternator from the main fuse block - still shorted the 40A fuse (excuse me, Nissan calls the fuse a "fusible link" for some weird reason). The (hopefully) attached URL w/ picture shows the fuse box near the battery. The red lead is pointed to the problematic fuse, the black lead is pointed to where (I believe) the alternator is connected. In this config, IF I insert a fuse it still blows (again by only turning the key to ACC). So, barring pulling out all of the relays/fuses under the dash, I'd like to look at the starter as that (I think) is always powered. I'm in the process of reviewing the wiring diagram from the FSM.

http://imageshack.com/a/img922/3329/D8yLEu.jpg

[Blindaviator]

The main power to the starter is direct and always on (unfused as far as I know) so it is unlikely to be the issue or it would melt the battery wire supplying it...
However the power to the solenoid switch is powered with the key so that could be the culprit (although that wire should only be supplied power when the ign key is in the start position)... There are only 2 wires attached to the starter, main power from the battery and the starter solenoid switch power (which is supplied through a relay)...

[pathfinder2001_green]

Removed all fuses/relays under dash. Turn key, blown fuse. In theory, the car should be completely "depowered" except for the starter (I *guess* it could also be the fuse block itself). I get the starter solenoid should not be energized until the ignition is in "on" position but I really don't have anything left to check. 2 fuse/relay blocks (under dash & under hood) & 1 relay block (under hood), right?

Appears that getting the starter off or even accessing the battery wire is a PITA, so trying to eliminate all other possibilities.

Thanks for your help

[pathfinder2001_green]

Could the ignition switch (in the steering column) be the culprit? Easy to check or worse than the starter?

[pathfinder2001_green]

AND the starter "terminal 2" (small wires) is disconnected = still blown fuse

[Blindaviator]

Could the ignition switch (in the steering column) be the culprit? Easy to check or worse than the starter?

I haven't messed with the ignition switch on these trucks yet but with most cars the switch is on the top side of the column down near the floor and you have to drop the column to access it... Will need someone with more experience with these trucks to tell you better how easy / difficult it is and if it's in the key or down on the column... But rule of thumb is they don't make access to the switch easy to help prevent theft...

But to answer yeah it could be the switch... Don't know of any reliable way to test the switch for shorts other than a volt / OHM meter to test for continuity to ground from any of the acc connections... The Ign switch is usually something that either works or doesn't and when it doesn't then it usually will just fail to activate the acc and / or starter rather than shorting out... Mostly what I have found that causes the ign switch to fail is people (usually women) have LARGE amounts of items on the key ring making it exceptionally heavy... That will cause excessive wear in the switch over time from the weight and the constant swinging as you drive...

[Blindaviator]

Removed all fuses/relays under dash. Turn key, blown fuse. In theory, the car should be completely "depowered" except for the starter (I *guess* it could also be the fuse block itself). I get the starter solenoid should not be energized until the ignition is in "on" position but I really don't have anything left to check. 2 fuse/relay blocks (under dash & under hood) & 1 relay block (under hood), right?

Appears that getting the starter off or even accessing the battery wire is a PITA, so trying to eliminate all other possibilities.

Thanks for your help

Yeah 1 fuse block under hood and dash & one relay center under hood...
No real way to disconnect the fuse block to test as I think that would also unplug the ign switch... Not 100% sure on that though...

It should, in theory, be without power but turning the key to acc and fuse blowing says it still has some power but at least 90% of the car has been eliminated now... You might try disconnecting every connection under the hood you can find (you will have to remove the engine cover to access most) and see if that makes a difference... I'm not sure what would still be powered by the ign fuse without all other fuses... Possibly the heaters in the O2 sensors?? Disconnecting all the plugs under the hood would remove most of the sensors from the possibility of shorts (the O2 sensors plug in on the top side of the engine, one near the oil filler neck and the other on the passenger side, top rear of engine)... May be a short in the transmission electronics?? Try unplugging the harness from transmission underneath??

Yeah dropping the starter is not easy and it is doubly difficult if it's a 4x4...

[rgk]

Disclaimer: I'm going off the 2001 FSM here, and not the 2001.5.

Per EL-13, I'm wondering how you have power to your ignition switch 'accessory' function without the accessory relay (Assuming you pulled all relays). Check EL-374 to see its location and make sure you pulled it. Not sure if the blower motor relay is the same relay, but if so, maybe you can swap those two out.

If that doesn't work, try looking at EL-17 to find out what shares a ground (M77, M111) with the ignition switch. You might have a short to ground somewhere. It makes sense that the headlights would work, as they don't appear to share a ground with the ignition switch 'acc' circuit.

[pathfinder2001_green]

Solved.

Some clown apparently had an aftermarket ______ (fill in the blank, sound system) installed and when they sold it, just decided to cut the wires to the whatever. Part of their install was a Bosch relay tucked up under the dash near the fuse panel. Disconnect relay, short went away. What helped A LOT was following the guidance in both the "General Information" & "Electrical" sections of the FSM. Using the multi-meter and that guidance I was able to determine the short was somewhere under the dash.

[Blindaviator]

Glad to hear you solved it... Electrical problems are ALWAYS the worst...

After your last post I was thinking about the sound system... I know these trucks have OEM amplifiers in there and I began to think maybe one of them was shorted... Thoughts weren't that far off the mark it seems...