Did I fix it?

LilHammer97

LilHammer97

TJ Enthusiast
Joined
Jun 19, 2019
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213
Location
Huntingdon, TN
I have a 2004 jeep wrangler SE 2.4l with a 5 speed trans.

Recently I got my jeep stuck on a trail in some axle deep mud (accidentally, I'm not a fan of mudding). And after I shut it off so I caould call a friend for help my jeep would only crank but not start (meanwhile its still in the mud.) So I stopped trying to start it and waited for recovery. After we got it pulled up tbe trail and back on level ground we tried to start it again for about 30 minutes or so while testing for spark and fuel. We then found out I was not getting fuel so we started checking fuses and found my ASD fuse (30 Amp j style) was blown. We popped a new one in and it started and ran just fine but now the dash volt meter was fluctuating between 12 and 14 volts. It drove just fine for a week and showed no other symptoms besides that one gauge.

Skip to yesterday and the "Check Gauges" light pops up on the way home and and I look up to see my volt meter down close to 9. So I high tail it trying to get home just to run my battery dead. I called my friend again to come jump me and I realized that my ASD fuse was blown again. So I popped a 40 Amp fuse in (all I had left) and got it home.

When i got home I unhooked my battery just to be safe. The next morning I went out and replaced that 40 Amp with the correct 30 Amp fuse and jumped it off. I let it idle for about 20 minutes and nothing happend so I took it for a test drive just to have that fuse blow and me get stranded again. So I get it home and replace the fuse once again and test the battery and it was showing 11.27v at the post while engine off
11.72v at the post while running
11.72 at the alternator while running.

So I take my battery and alternator to the parts store for testing.

The battery came back good besides being undercharged.

Alternator failed the DC test.

So I grab a new alternator at the parts store. I forgot the part number but I opted for the one that puts out more. And I had my battery charging all night.

Fast foward to this morning and my battery reads 12.92v and my alternator has arrived. I went to store and picked it up got home and slapped it on. Double checked all my wiring and still didnt see anything out of the ordinary. So I hooked up the alternator and my battery and BAM! It started. So I let it idle for about 5 minutes then grabbed my multimeter to check and this is what I found.

With the engine running without any accessories on like the lights or radio
13.87 on battery post
13.90 at fuse box
14.02 at alternator

Then with all accessories on (headlights, interior lights, radio turned up to 20, subwoofer with 600 watt amp, and a/c blowing full blast)
13.70 at battery post
13.71 at fuse box
14.01 at alt

I am going to wait about an hour and go perform the same test but with my light bars hooked up and running to see if there is any significant draw on the power. I also did spot on thing and that was my belt tensioner was hopping up and down quiet a bit when I had all the accessories on. Can that be a big issue?


My big question is why was the ASD blowing? (Suggestions)

What does my ASD fuse work with?

Did it sound like my alternator was just bad bad?

And can a bad Alternator cause all these issues?
 
Like in my reply message to you earlier, your alternator was likely just packed or at least seriously contaminated with mud. The usual fix for that is pretty simple, flushing it out with copious amounts of WD-40... like a can or two. You can even flush it with a hose first followed by flushing the water out with lots of WD-40. That could conceivably cause fuses to blow due to the moisture/mud trapped inside.
 
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In addition to what Jerry said, as voltage decreases current rises to do the same amount of “work”. I’m theorizing that when your alternator wasn’t charging and depleting the battery charge the current for the ASD circuit was rising to the point it blew, which was 30 amps.
 
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Daryl said:
In addition to what Jerry said, as voltage decreases current rises to do the same amount of “work”. I’m theorizing that when your alternator wasn’t charging and depleting the battery charge the current for the ASD circuit was rising to the point it blew, which was 30 amps.
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That's not quite how Ohm's law, work, watts, current, and all that works. The motor presents a mostly fixed resistance (aside from a mild temperature coefficient) to the voltage so as the supply voltage drops, amps drop, watts drop, and the amount of work that can be done drops. In other words the motor's resistance, its load presented to the battery, does not vary in step with the voltage.
 
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Jerry Bransford said:
That's not quite how Ohm's law, work, watts, current, and all that works. The motor presents a mostly fixed resistance (aside from a mild temperature coefficient) to the voltage so as the supply voltage drops, amps drop, watts drop, and the amount of work that can be done drops. In other words the motor's resistance, its load presented to the battery, does not vary in step with the voltage.
Click to expand...

Just played with ohms law, forgot all about that resistance thing. Thanks for the correction. Always learning.
 
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@Farmboy666 it only seems to do it when my A/C is on.

@Jerry Bransford I ended up taking the alt off and it sounded like something was not good with it. It made almost a grinding/rubbing noise. So I went ahead and replaced it. I'm going to go test drive it right now. I'll post back with any new findings.
 
LilHammer97 said:
@Farmboy666 it only seems to do it when my A/C is on.

@Jerry Bransford I ended up taking the alt off and it sounded like something was not good with it. It made almost a grinding/rubbing noise. So I went ahead and replaced it. I'm going to go test drive it right now. I'll post back with any new findings.
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I thought you were just talking about electrical accessories such as lights etc. Yes the AC will put more drag on it and maybe its about shot but shouldn't cause a charging issue.
 
Could need a new tensioner too. How does the belt look? If it is the least bit questionable then I would replace both. Keep the old belt as a backup. Or does the '97's have the type of tensioner that can be tightened with a bolt, not with a spring like on my '06?
 
I'll bet the bearing is shot. Get a new one on the quicker side before it creates a bigger problem.
 
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