Hello new here, looking for some help with an issue my wife’s daily driver is having. It's an 01 Montero Sport LS with a 3.0. Saturday night we were driving down the road and the truck almost died the radio went off and the tach dropped to 0 and the truck jerked when I slowed down and the lights went very dim. I got to a parking lot and killed it and it wouldn't do anything but click when I turned the key to try to crank it back up.
Sunday morning I pulled the alternator off (the one that's only two months old) thinking that was the issue again but the alternator tested good. Then I pulled the battery (only two months old also) to have it tested and it was fine. So I got the battery charged and drove the truck to Autozone to try to have it tested there.
The guy put the machine on it and it came back with "no output check alt wire" so he said maybe it's a fuse. I pulled the cover off and sure enough the 100 amp fuse in the corner of the fuse box was blown. I bought a new one and put it in and truck cranked right up with no service engine soon, battery or brake light came on. I turned the A/C all the way up and turned the radio on and the lights and everything seemed fine! Well I set off to bring the truck home and I got about 4 miles from autozone and the radio went off. Then about another 10 miles down the road the tach dropped to 0. Then when I slowed down for a redlight it jerked again and acted like it wanted to die, but didn't. Anyway I got it home and the SRS light came on but the brake, battery, or service engine soon light never came on. I killed it and tried to crank it back up and nothing but clicks again. So now it's sitting in the driveway!!
I can jump it off and it runs for about 1-2 minutes then dies. The radio won't do anything even when jumping it off, the tach works for about 10 seconds then drops to zero but the rpms are still where they should be until it starts dropping and then eventually dies. The SRS light stays on as well as the battery and brake lights..

I would really appreciate any insight you guys have. Have you ever heard of this happening?

Thanks,

 

Have you checked your ground?

 

No. Where is the ground I need to check? The only wires coming off the alternator are the two that are in the plug and then the one that attaches with a ring terminal with a nut. All of the wires are wrapped in electrical tape and split loom. I was scared to start unwrapping them.

 

To check the alternator, turn on your vehicle, disconnect the battery it should stay running off the alternator....if(and i write if) the alternator is doing its job, if not you have an alt issue........also your battery should be checked to see if still in good working order. All batteries give out 3-4 years after purchase, no matter how much it cost you or if you have the best one ever made......also check "the big 3", wiring from starter to battery, from battery to alt, from battery to chassis.......wires should be not corroded, and flexible without cracksnor burn marks and connectors should be cleaned and tightened.

Any questions let me know, glad 2 help.
Lg23

 

I had the battery and the alternator tested yesterday and they came back that they were both good. They both are only 2 months old. There is no corrosion anywhere. I'm going to replace the terminal on the end of the negative battery wire today when I get home.

I've always heard to test the alternator the way you say but I also heard if you do that on a newer vehicle like this it can mess up the computer. I certainly don't want that.

 

I just replaced the negative terminal and checked the grounds right next to the battery, down on the frame, and above the A/C compressor on the engine. I sprayed all of them with degreaser to clean them.
Well I jumped it off and it stayed running the radio came on tach worked and all the lights were bright. Then I decided to go for a test drive and I drove about 5 miles around the neighborhood. No problems at all on the test drive so I drove up in the driveway and decided to kill it to see if it would restart and it did but it was kinda slow. Then here it goes again the radio went off, the tach started jumping then fell to zero and the truck eventually died! I don't understand why it ran fine again for 5 miles then started acted up?????????????

Any more ideas.

 

You may have issues from the cable running between the battery and the alternator. Follow it from the battery to the alternator checking for damage to the insulation that may intermittantly touch ground (which may have caused the fuse to blow) and for other visible damage. Since you've had the alternator out before- try checking for continuity from the alternator side of the wire to the battery + as you jiggle the cable back and forth. There may be a break inside the cable.

JJ

 

When you say "check for continuity" you mean, with a multimeter to take a reading at the battery, from the positive post to the negative post. Then another reading from the end of the wire where it attaches to the alternator to a ground point and see if they are the same reading. Right? I don't want to sound like a total idiot but I've haven't messed with electricity or wires very much before.

There are only 3 wires running to/from the alternator it shouldn't be that difficult I wouldn't think? I hope not.

It has me stumped as to why it ran fine for so long (about 20 minutes) when I first jumped it off yesterday, when I jumped it off a second time it was just like Sunday when it would only run for a minute?

Thanks I'll let you know what I find out.

 

Just food for thought, ................new parts sometimes-have issues. (deffective)
TRY TO REPLACE WITH OTHER TO TEST "NEW" ALT AND BATT. IF YOU CAN JUST REPLACE WIRES ALL 3.

 

I understand that, but the problem is they won't give me another one until this one fails their test. I really don't want to spend another $200 for an alternator unless I know beyond a shadow of a doubt that it is the problem. If it is then F%$K Autozone and I'll buy a mitsu alternator.

If the wires check out good I may see if I can get one from the junkyard to test that out. With that said what years have the same alternator on them?