A big electrical spark, a puff of smoke and know I need some advice

[goin camping]

Jeep is a 95 YJ with the 4.0 and a 5 speed.

In a hurry and cross connected the pos/neg while jump starting the jeep. Started the jeep up and when I disconnected the cables the jeep died. That's when I realized my mistake. Jeep quit running when the cables came off. Connected properly and it would start when hooked to the cables but dies when the cables come off.

Went a got a new battery and it started and runs fine but the guage shows no charging. Needle halfway towards the red. Increasing revs does not move the needle towards green.

Is there a fuse I should check (and if so where?) or am I on my way to get a new alternator?

 

[bob91yj]

Check the Maxi fuses under the hood, black box in front of the battery.

 

[goin camping]

Check the Maxi fuses under the hood, black box in front of the battery.

Just did that. I saw no evidence of a fried fuse. Do you happen to know which fuse it is? I don't have an owners manuel nor can I find it on the internet.

 

[bob91yj]

The legend is printed in the lid.

Second one in 50A is AltPwr1, third one 50A is Fuse Block, and the sixth one 50A is AltPWR2.

 

[birdiecat]

By any chance is you alternator charging. Because if the alternator is not charging the engine will run off of the battery on till it is disconnected.

 

[goin camping]

By any chance is you alternator charging. Because if the alternator is not charging the engine will run off of the battery on till it is disconnected.

According to the guage it is not. I found an in line fuse but in the tone of today. It will not come apart.

 

[shortbus4x4]

Alternator is most likely bad. It will run with the jumper cables connected but disconnect them and it dies. If you had a dead battery and an alternator that was charging it would keep running with the jumpers disconnected.

 

[Bigjerm]

Yep has to be alternator. The dummy test is to crank your vehicle and pull the cables off the battery. If it keeps running then it isn't the alternator


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[Jim K in PA]

Pulling cables on a running engine with a good alternator is a good way to fry your alternator.

It is most likely the fusible link, not a fuse in the panel. The fusible link is a short section of small gauge wire in the main lead between the alternator output and the power distribution center. The puff of smoke was that little section burning away. It did what it is supposed to do, but now you need to replace that section of wire.

 

[Bigjerm]

Never fried one before and you will know pretty quick which one it is. I have seen first hand people crank, pull their battery to lend to another rig and drive off a trail and never have an alternator issue after that.


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[Eaglefreek]

Pulling the cables to check to see if the alternator is working is a bad idea. It might have been ok in the old days, but there are too many computer controlled devices on vehicles nowadays that can get damaged doing that. I'm pretty sure the voltage regulation is done by the PCM on your Jeep and there is not a voltage regulator on the alternator. If it's not a fuse or fusible link you may have to replace your PCM. NEVER be in a rush to connect jumper cables or connect the cables to your battery. I never let anyone connect jumper cables to my battery. I always do it after triple checking I'm connecting to the proper terminals. I don't go by the color of the cables going to the battery on the car. I look for the markings on the battery and then trace the cables to see which one goes to ground. Sounds anal, but the damage done could be costly, if polarity is reversed.