Hello all, I have a 02 Montero sport XLS 3.5L that is giving me a headache.lol. My daughter drove home one night and killed the battery,She said all the dash indicators came on flashed,radio cut in and out.I go out and check it battery is dead.Charged battery up and cranked it and put voltmeter on and check it running and not running and no voltage increase battery starts to drain as its sitting running,long story short.buy new battery and alternator,change battery ends clean all cables.Put everything on including new belt. Start it up its showing 14.5volts and thought I was done.she drives it one day and all the same starts happening again but battery doesn't go down but 1 volt.Stated checking volts after charging battery back to full and it would start off good put a load on it and looked good.Shut it off re crank it and voltage drops will not come higher than 12volts everything on its at 11volts.So I take alternator off carry it back thinking its bad they test it twice shows good.Tells me to change belts it may be slipping.done that no help.run a new wire from alternator to battery and it still messes up. Is their something Im overlooking or is the alternator just jerking my chain..Thanks in advance I know this is to much to read.Sorry

 

How is your positive feed to the alternator? If that wire has a break in it, it may cause an intermittent activation of the stator and may look like the symptoms you describe. Hook up a voltmeter to it with the second lead on the negative battery. Then flex the wire all around and see if you get a drop in voltage.

 

Checked that and nothing different.Did notice that when I re-start the vehicle,the battery light doesn't come on after several re cranks.only comes on after I let it sit for about an hour or so. Very odd acting. It will auto-lock the doors just sitting with no key in the ignition and running sitting still. hope its not the computer.

 

It is possible you have a short to ground somewhere. If your doors "self lock" this is at least likely cause. Check the wire loom condition at the doors (especially driver door). Do the same test - wiggle the wires around to see if you get something.
You can also do a following test - pull the fuse responsible for the power door operation. Then drive the vehicle like you normally do and see if the troublesome alternator/drained battery behavior returns. If it doesn't you may want to check your door wire looms to see if there is a short there that is causing the major power drain and the symptoms you see.

 

Is their anything on the vehicle that isn't OEM ?????

 

Tried the door lock and wiring and it didnt help. Everything but radio is factory.If I go crank the vehicle now it will show 14.4volts running,cut the headlights or fan on and it will drop to 12volts,cut them on together and it will drop to 11.5volts.cut everything back off and it comes back to 12volts,cut off the vehicle and re crank it and will show 12volts. The place that rebuilds alternators and starters told me the Alternator was showing good,they tested it twice.I dont know whats going on with it.

 

That is totally bizarre... Are you saying that when you turn off the lights (cut them) the voltage drops?

 

Just for ****s n giggles I would pull the radio fuse and give it a check. Just to see as it isn't OEM...
How can the voltage drop if you kill the lights???
We need more feedback bud.

 

Yes if you turn on the headlights soon after starting vehicle and checking voltage it will be at 11volts not the 13 to 14 it should show with a load. I ran a wire from alternator to battery and it still stayed at the low voltage. When you turn off everything the voltage will not go back to 14.3 but only comes up to 12volts. New Battery and gates belt. Auto shop tested alternator twice and said it was good. I can pull the fuse on the radio but dont think its the problem. when it quits raining I'll mess with it again

 

ti2002 - if you battery voltage shows 11 v. when engine is running - it means you are running everything on battery and alternator is not charging the system. I'd suspect the alternator. You need to run the on the vehicle tests to check alternator function. They are a bit complicated, but doable with a pair of ammeter and a voltmeter.

But before you go down that route - how are your connections at the battery? Pull off the battery clamps, clean really well. Also, check the connection between battery clamp and the fusible link box (the little plastic box connected to the positive lead). It is possible to get enough corrosion there to cause an intermittent condition. If possible - take apart the connection and scuff the metal contacts with an emery cloth. On my full size Montero with a 3.5l engine, there is a wing nut that holds the fusible link box connector to the clamp. At one point I was getting a charging system warning and it was due to corrosion in that spot. While there, also check the fusible links. I've seen them to be cracked but the two contacts did not fully disconnect (hairline fracture). This caused an intermittent and unpredictable not charging situation and all sorts of battery related issues. It was on a different vehicle and a different style of the fusible link, but it worth checking anyways.