Upon having put a 100 or so miles on the new QX4 we noticed a smell like burning plastic coming from under the hood. I investigated further and pulled off the fuse box cover on the passenger side and here is what I found...



close up...


I am like 99.9% postive that this is the cause of the smell. You can see it has melted around the connector and was very hot

What is going on here???? What do I need to do to fix it??

My thoughts..

voltage regulator (build into alternator...right? thats how it is in GM stuff) malfunctioning and providing too much voltage?

I believe your alternator is outputting full amperage (110 amps), overcharging the battery. Very bad for the battery. The heavy current is causing the heat.

The voltage regulator is internal in the alternator, yes. This could be a problem with the alternator (internal short, bad regulator), or a wiring problem. Since the car is new to you, inspect the alternator / fuse box / battery cables for fresh electrical tape and other signs the wiring has been worked on - was the car in an accident?

The alternator on the 4wd models is in a tight spot and is a tough job to replace as alternators go.

In the mean time, I would drive it as little as possible.

I think the battery is being seriously overcharged, so I would check the water level in each cell. It will boil off quickly. Oh, if you have a voltmeter check the battery with the engine off - you should see about 12.6 volts. It is possible the battery has an internal short - thats not common but could also be a problem here.

I would also unbolt the fuse box and see how much damage there is to the underside of it - you don't want it to short to the body. I can't really tell from the picture.

Just to be on the safe side -batteries produce hydrogen gas, and lots of it when being overcharged. Don't produce sparks, etc. around the battery while checking it.

Or maybe have an auto electrical shop look at it if there is one in your area.

Thank you for the imput. When the car was bought the old owners had put a new battery in. I will first see if they even put the right battery in (these were the same people afterall who had just threw on a 18 inch wiper for the fronts)

i will look at the alternator and see if any thing looks like its been done recently. I did notice the alternator was in a strange spot on these.. Would putting a volt meter on the alternator and seeing if the voltage is above the acceptable 13.8 to 14.8 range be a way to confirm a bad alternator causing this problem ?

i will also try to get a view of under the fuse box. No accidents recently. The only thing that car fax had on it was way back in like 06 was a minior incident and that was on the drivers side door not the front

Here is the battery they had in it. It is a crappy walmart Everstart brand. It comes up as a marine battery. Could that be part of the issue? The voltage of the battery with the car off (and cold) was 12.62

http://www.walmart.com/ip/EverStart-24M ... y/16782694

Ok so ran some voltmeter tests on the car here is what I found. Everything seems to be in spec. See pictures..


First here is what my battery terminals look like. Does this all look stock?


Here is the battery with the engine off. (it had just been run for a few min to get it into the driveway which i would imagine the increase from the 12.62 measurement i got this morning with engine cold came from)


This is the engine running at idle testing on the battery terminals


This is the engine at idle testing at negative battery post and the spot where its melting


This is the engine running at about 3000rpms testing on battery terminals


This is the engine running at about 3000rpms testing at negative battery post and the spot where its melting



The spot where it is melting... should that even be getting hot at all? Would that mean that somehow that connection is getting grounded to the body when it shouldn't be?

When I had the engine idling and the meter on I tried having my girlfriend turn on and off the radio, headlights, Air conditioning but no spikes or anything like that.

The voltages look ok. The battery connections look like the factory originals. You need to replace the negative battery cable connector. It has a penny crammed in it to get a tight connection. While you have the negative terminal disconnected, use a wire brush and clean the inside of the positive terminal, then retighten that.

I don't think the penny has anything to do with your problem.

The terminal getting hot is connected to the cable that goes directly to the back of the alternator. It should not get that hot. That terminal is the 120 AMP fusible link, and the wires go from the fusible link directly to the positive battery terminal. They are the wires coming from the bottom of the fuse box and going to the red part on the positive terminal.

With both battery cables disconnected from the battery, you can loosen that nut, remove the cable, and pull the fusible link out of the fuse box. See if there is corrosion on the terminals in there, and clean as necessary. Then clean the cable connection from the alternator, and put it back together. Corrosion can cause resistance between the alternator and the battery, which can cause heat also.

After you clean everything up and retighten everything, you can run the car awile and see if that connection gets hot again.

If it does, it is probably shop time. A mechanic would measure amperage output from the alternator to see if it is too high, then figure out why. It is the amperage that causes the heat.

I don't know for sure, but the battery may be new because the old one got cooked by the alternator.

Anyway, hope that helps out!

Good spot on the penny I had not even noticed that before. I will give your suggestions a shot and follow up.

I am certain that your assumption on the battery being new because the old cooked it certainly right

Ok here are some pictures....


First close guess on the penny it ended up being a washer.


This is the ground cable for the battery post (arrow where it looks to be grounded to the body)


It looks like it is grounded once to the body... (close up of ground to the body)


... and once to the engine block. Is this correct?



Here is the under side of the fuse box...


Close up


It looks like everything is OK besides that spot...right?



Does this guarantee that my problem lies within the alternator? It looks like its awful to get to...Is there a guide for this at all in the How to section?

I can't say say thanks enough for the help

Had to replace my alternator two weeks ago.
I'm fairly handy and do a lot of work myself.....but not this one.
Unless you have a hoist, I wouldn't recommend doing it yourself.
The alternator has to come out the bottom. You can't take it out from the top.
It's a royal PITA job.
The mechanic who did it for me wasn't pleased. Good thing it was a set rate to replace, and not pay by the hour.

Would you agree that the alternator has to be the cause of this?

OK, first of all, I had to replace my alternator for a different reason.
It just flat out failed.
My battery kept going flat, and all the lights on my dash would come on, then my truck would die. Not fun.
It wasn't charging anymore, so I had it replaced.

The voltage readouts you provided indicate a working alternator.
I'm a contractor, and part time electrician, and have seen situations like this where connections get hot, and sometimes melt light switches, dimmer switches, or even appliances.
(Usually a breaker or fuse will pop before a fire breaks out.)
A couple of reasons why this happens: Too much amperage for the gauge of wiring. Example: 20 amps running through a wire designed for 15 amps.
The second, and usually the main reason, is loose or corroded connections.
If they are loose or corroded, then the resistance increases, and the connection heats up.
I suspect that is your problem (given the pictures you've posted).
Looks like you should replace your ground wire from the battery, and you'll probably have to find another fuse box assembly (wrecking yard will be the best place)
Keep us posted.

First, a correction. I assumed that the lug which the cable from the alternator attached to was the fusible link. It is not. The fusible link is the white box in the center of your first picture. The lugs the black/red cables attach to appears to just be a connector.

Here is a link to the wiring diagram (on page sc-20):
http://www.nicoclub.com/FSM/QX4/2001%20 ... System.pdf

Not sure whose pink fingernail that is in the last picture, but I will assume it is your girlfriends...

As to your questions:

There is one more ground point on the negative cable down near the bottom of the fender just before the cable turns upward to go to the engine block - at least it is that way on my 02.

The fuse block looks ok - I think you caught things in time. Some melting, but not bad. I would unbolt the large black / red cable on the underside of the fuse block, clean it up, and retighten it. As a test, I would set the voltmeter to ohms, and check the resistance from the top lug of that connector to the positive battery cable terminal. It should be zero ohms. Probably will be, but its an easy check.

Then check resistance from the top lug of the connector to the other end of the short black / red cable where it connects back up to the bottom of the fuse box. Should be zero ohms as well.

Clean up your ground points on your negative battery cable, and retighten. After you have cleaned the connections for the large black / red cables, zip everything back together. You may get lucky and find that the spot where it was overheating just needed to be cleaned up and retightened.

Can I guarantee it's the alternator?. No, you would need to check all the circuits going to / from the alternator in the wiring diagram. There could be a bad connection / corrosion, etc. causing a problem. The alternator has to get correct voltages from the smaller circuits for the regulator to work properly.

If the connection still gets hot after this, I do think I would let somebody check alternator output and see if they can figure out what is causing the problem.

Oops, meant to say I don't think the marine battery is part of the problem.
Buzzman posted while I was writing - a new cable would be better - that one is looking pretty rough.

I have read that an intermittent open ground could be the problem. When the ground is open the alternator is asked to put out maximum amperage and that can cause a lot of damage.

Any else confirm my thinking on this one?

I had thought that the alternator technically passed it's volt test by staying within acceptable range. The only reason I hadn't ruled it out was the built in voltage regulator maybe doing something funny intermediate

There have been a couple times when the car would start up great (no hesitation cranking at all) and then maybe 15 min later it would not crank and at like the battery was dead. Sure enough I put my jump box on it and it fires up just fine.

Would this be consistent with a intermittent open ground?
Where do i start in order to confirm this. I can replace the fuse block but if it is just going to melt again I would like to find the issue first if possible

4xq wrote:
Not sure whose pink fingernail that is in the last picture, but I will assume it is your girlfriends...

You didn't like my choice in color? jk yes those are my girlfriends. Its her car so I told her she has to help

I will try those suggestions a try and come back with results.

When i was inspecting the ground cable from the battery. I did notice what looked like another spot on the inside fender for it to attach to but it looked like it was just a zip tie spot for keeping things neat and where the should be so i didn't think much of it being not attached there

And by replacing the ground cable you are referring to the ground cable that goes from the battery post to body to engine block right? (the one in the 2nd picture after the picture of the washer)

Not the the cable that goes from the alternator to the spot where its melting.

I was 99% sure this is what was meant but wanted to confirm

Having a washer in your negative battery terminal connection would be a good reason for poor grounding. That would affect starter operation. See if the starter problem doesn't go away now that you are fixing up the negative battery cable connections / grounds.

The intermittent ground with respect to the alternator - there is a grounding lug on the back of the alternator - you will need to remove the alternator to get to it I think. Make sure the battery is disconnected if you decide to work on any of the alternator connections.

Yes, the alternator has passed the voltage test - highest I see in your photos is 14.3. But it can go to maximum amperage at that voltage if there is a wiring issue or there is an internal alternator problem. It is clearly working, the question is whether it is overcharging by going to max amperage. The volt test is only 1/2 of the question.

I don't think there is a guide on here about removing the alternator, but you could search older posts and see what info comes up.

Anyway, bedtime here. I'll try and check in tomorrow.

4xq wrote: As a test, I would set the voltmeter to ohms, and check the resistance from the top lug of that connector to the positive battery cable terminal. It should be zero ohms. Probably will be, but its an easy check.

This is the result with the positive battery terminal fully assembled (the red plastic thing connected)..looks good


This is the result with the positive battery terminal NOT fully assembled (the red plastic thing NOT connected)..no pass this time (is this how it should be??)

Then check resistance from the top lug of the connector to the other end of the short black / red cable where it connects back up to the bottom of the fuse box. Should be zero ohms as well.

This looks like it checks out as well



You would think that if the amps where way out of range being to high that it would blow the main battery fuse here right....?





I am going to clean connections up now and see what happens

Ok So I think I have made some progress...


Every connection all cleaned up and shiny...


I didn't want to go through the trouble of reinstalling the battery just to test the system just to take it right back out if it didn't work so I used my jump box. I reassembled the positive terminal back together with the red plastic piece attached. I just bypassed putting the big black/red cable coming from under the fuse box and cable coming from the alternator through the plastic housing and just bolted them together so I knew I was getting a solid connection...



Close up of the connection (this was the original problem connection that was melting the plastic)



Fired the car up and it let it run for about 10 min or so and no sign of any heat!!!! It used to be way to hot to touch! I put a full load on the alternator as well. With headlights on, all 4 heated seats on, navigation, and stereo all on and this was my result.



So i guess everything is looking good right now. i am going to but it all back together now with the actual battery back in and will update with results

So I got it all buttoned back up...



Drove it around for a couple miles each direction from the store and it has stayed cool to the touch!

So for now on this issue it is hopefully case closed! Thank you all so much for your help on this! Saved me throwing an alternator at the problem!

Looks like a good job of cleaning everything up! Bet your starter problem is fixed as well.

Anyway, glad it all worked.

Yes i hope it clears up the starting issue as well. I meant to check the fuel pressure today but forgot. i am also unsure of where the test port is? Do you know?

I am assuming that it should be in the 35-40psi range?

You know, I have not done any work on my fuel system other than one fuel filter and then a bottle of Techron every six months. I would have to look up where the fuel port is.

I posted the link to the electrical portion of the service manual - in that same directory are all the other portions of the service manual.

The EC or engine control section has the procedures for the fuel pressure test. I do recall there are two pressures - one with the pressure regulator connected, one without.

You might want to download all the sections since you have other projects on the list. It is actually a pretty decent manual. It always gives testing procedures for "Consult II" first, which is the computer the dealers use, then after that are the manual testing procedures. Once you get that, they are pretty useful.

4xq,

thanks for the tip.

I did end up finding it. Here it is in case anyone else is wondering...



I will give it a shot tomorrow

Just to follow up here. Since the qx4 returns today I decided to finish up this plastic burning job nice and neat as if it never happened. I was at the parts yard anyways and they had what I needed.

Here is what we got to make it all like new and actually mount like it is supposed too!




New negative battery cable as suggested by buzzman and 4xq
New black/red short cable that connects to the underside of the fuse block (mine old one was a little crispy)
New fuse block (with no melting)
New cover (with no melting)
New Underside fuse housing/mounting box (mine old one was cracked and busted all over)
New battery tray (mine never had one of these and figured it would help prevent further rusting)

Well, since you are fixing it up, think about spraying the battery tray area with some Rustoleum rust reformer to stop the rust, then cover that with a rustoleum primer.

Worked pretty well on mine - I had quite a bit of rusting in that area as well.

Yea I think the rust was from the previous owners battery that over heated and probably leaked out corrosive material everywhere.

There was a lot of rust..


I had some Rustoleum in laying around, 4xq great idea on that one... looks much better


I figured while I was at it I might as well re paint the battery support bracket as well. It had a good deal of rust as well.


Got the battery tray back in there...


New Fuse block with no melting and bottom cover not cracked and busted up and mounts correctly


All back together and hopefully a job done and done right...