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Discussion Starter #1


This post's objective: seeking an answer to a somewhat odd,not seen by me before behavior, exhibited while crawling rocks with it.

Model of JK: a 2011 JKU with slight modifications

Issue: a sudden ,full , complete loss of power or shutdown of the entire electrical system , (even internal courtesy lights).

When: this occurred at the immediate moment that an impact occurred. This impact was completely "towards gravity" vertical in direction. Downward with travel of 8"-10" of front end. Striking downward upon flat,rock ledge.

further details:

I was crawling with friends ystrdy.
On series of ledges.
At one point, my JKU slipped off a ledge ,dropped about 8" down and impacted the pssgr side front framehorn extremely hard. Very hard. It hurts to remember how hard it was a day later.
It doesn't matter but the actual point of impact was the stub of the bracket where the stock "bashbar" I cut-off long ago was. Right down onto that box on right framehorn. That, again,isn't important. No damage except some slight steel mangling to that you see yellow arrow pointing at:



( fwiw: That's only still there because the ExpeditionOne basicDX winch plate connects to it so I can't cut it completely flush to frame. As I said, all that is not important....)


...
so, when the front slipped off and hit/landed upon the frame there, the Jeep just went black. As in , no power, electrical nor engine, no chimes , no dash warnings , no key touch , nada.

Just BAM! then everyone heard it shutoff and I announce no power+ "wtf?!"...

I grimmaced and slowly turned key to "off". Collected myself ( it was hard hit) then turned key & she turned right over. WTF?

I looked in user manual about the varying levels of passenger restraint ,ORS, the airbag different activation levels , but all of that pertains to forward or rearward impacts. Nothing about downward . I searched far and wide on internet. There's some questions. about '...can you deploy airbags offroading...' but nothing like what I experienced.

Can an impact , downward , of great degree cause some
power down function ? It wasn't just the fuel system or engine; it was total Jeep go dead dead. No headlight turn on , no festoon overhead lamps , no radio no aux nothing.

I honestly thought it was broken. Afterwards, the rig acted as though nothing happened and resumed crawling.

:confused:

Just wanted input from others if they've experienced similar.





( oh. I made the obstacle, it took me 3 years to beat it! :thankyou: )


 

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Discussion Starter #4 (Edited)

Yup.

(edit : add photo)

here , you can see how tight the post clamps are ,almost:

I run those brass terminal HD clamps & check before every ride. I have a diehard plat that I had also verified was solidly seated with the retaining wedge.
I'd hang upside down off the two terminal cables based on my
confidence in their clamp connection integrity, if that unlikely scenario could ever take place ....

Could shaking or smacking down upon the winch & it's solenoid do anything like this ?
Maybe the actual fuse or TIPM flexed or something ?


What's odd is it fired right back up .



 

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Discussion Starter #5
Not really sure what happened but...………….

Vehicles today have all kinds of safety systems including systems that do certain things during a crash or a rollover. Things like pre-tension the seat belts, turn off the fuel pump, even roll up the windows in some vehicles.

Commonly used to detect collisions and rollovers (but not exclusively) are 3 axis accelerometers. They can detect a crash or a rollover and take the necessary actions. My guess is that when you thumped the front of your frame on that rock, you set off one or more of those accelerometers and the ECU might have thought you were actually in a rolled over condition. Usually during a crash condition, the ECU does not kill power to everything, to the contrary it is doing things including setting off the airbags.

But in a rollover, the ECU probably assumes that gasoline is leaking from the vehicle and thus it would likely kill all power to everything and anything in order to prevent a fire. My guess is that is what you triggered. After the ECU realized you were not in a rollover, it restored power and everything was fine.

This is all just a guess on my part.

I will go with this; sounds feasible.

Thanks all ...

 

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It's probably a loose ground, and not on the Battery. remove the battery and follow the ground wire. Everywhere it goes, check for a loose connection, and tighten them all. This will cost you nothing but time. It could also be your positive.
 

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Discussion Starter #7 (Edited)
It's probably a loose ground, and not on the Battery. remove the battery and follow the ground wire. Everywhere it goes, check for a loose connection, and tighten them all. This will cost you nothing but time. It could also be your positive.



I check from battery post connections to each ground +ignition ,starter, all internal / external grounds on the Jeep annually. I have three Jeeps I currently upkeep myself , so , your advice is solid & I'll again check but I'm real OCD about everything ...


I'll report anything I find .

Oh, if y'all wanna make fun of me driving skills ( or lack of) , I cut out the section of video where I slip off ledge onto that frame. Of course it looks like a tap in video. It was a hard, stupid bounce . Awkward and you can't see the steepness in video. I like others reactions , heh...

( 00:10 or 00:12 sec mark )


:rolleyes:



(edit: I just noticed in this my LED taillights do stay illuminated from my brake-foot after bump. So, just the engine & dash went dead. I guess each tail being on separate side harness & circuit unto itself permitted them to still work.. But, it's even a bit more weird that those stayed functional ...

It's no big deal . Just a odd quirk. Damn fancy computer Jeeps.



Also: 12psi 'cause someone's bound to ask...)


 

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In that vid, it looks like you backed up after the hit. So it seems it was still running for at least a bit after you check the hardness of the rock.

I think that just makes the whole deal stranger now. Sorry:thefinger:
 

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Discussion Starter #9
In that vid, it looks like you backed up after the hit. So it seems it was still running for at least a bit after you check the hardness of the rock.

I think that just makes the whole deal stranger now. Sorry:thefinger:
yeah, it just rolled back when I let foot off brake as I checked that my teeth were still in my head. It does show the taillights when I hit brake, so who the heck knows. It was very very strange and I think the Jeep just did not like it is all....
 

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Discussion Starter #13



I know that $$$ tree isn't growing out front of my place, either. I'm just gonna treat the jku 3.8l the same , courteous & diligently maintaining it as I have my inline6 4.0l in my XJ . It will turn over past 400,000 me miles this year but there's no way the V6 is goin that far. We shall see.

But , I won't disassociate the electro-fuckery FCA baked into the JK until forced to kill it . Just me, personally...tho, I never use any of it ...I've never even activated the cruise control ...nor pressed that 'hill descent' button.


 

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So we should all just hotrod wire our jeeps Kowboy style? I mean, I have thought about it. An LT swap would have to be in the works at the same time. :idea: Likely a Holley dominator stand alone deal.... now I just need to find that money tree.......
There's one key thing that I'd say would trigger the hotrod style wiring being the smart move. Removing the dash. If you're getting rid of the dash, slapping a stand alone wiring kit in make sense.

Up until dash removal, you still need the TIPM, ECU and cluster to be happy and present. There's really no room for hotrod wiring in the equation.

I got lucky. Hotrod wiring was going to my phase two on my build. When I finally threw in the towel on keeping the stock dash, the tub was already stripped of all wiring and electrical bits. So for me, it wasn't a giant jump from one to the other, half the job was already done.
 

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Discussion Starter #15
There's one key thing that I'd say would trigger the hotrod style wiring being the smart move. Removing the dash. If you're getting rid of the dash, slapping a stand alone wiring kit in make sense.

Up until dash removal, you still need the TIPM, ECU and cluster to be happy and present. There's really no room for hotrod wiring in the equation.

I got lucky. Hotrod wiring was going to my phase two on my build. When I finally threw in the towel on keeping the stock dash, the tub was already stripped of all wiring and electrical bits. So for me, it wasn't a giant jump from one to the other, half the job was already done.



I want to be a Jeep electro-rebel but my Dash won't let me....:lol:


 

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The exact same thing happened to me today. While crossing a creek, I was having trouble getting traction so I tried using a tree stump (maybe 8” high). My wheel would not catch any traction so I backed off the stump and the Jeep landed with a thud. The Jeep shut off, dash went dark, headlights and everything shut off. At that point I could not start the Jeep. It was like having a completely dead battery. I checked fuses, cables, grounds, etc. nothing out of place. After an hour or so it started right back up. The only thing that I would add is that prior to the creek crossing I had done a considerable amount of winching through the mud. I run a single battery / stock alternator. I did get some dimming of the dash while winching.
 

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Discussion Starter #17 (Edited)
The exact same thing happened to me today. While crossing a creek, I was having trouble getting traction so I tried using a tree stump (maybe 8” high). My wheel would not catch any traction so I backed off the stump and the Jeep landed with a thud. The Jeep shut off, dash went dark, headlights and everything shut off. At that point I could not start the Jeep. It was like having a completely dead battery. I checked fuses, cables, grounds, etc. nothing out of place. After an hour or so it started right back up. The only thing that I would add is that prior to the creek crossing I had done a considerable amount of winching through the mud. I run a single battery / stock alternator. I did get some dimming of the dash while winching.
well , I'll be damned , it is precisely the experience I referenced & had ( see above) . So , I read all about the crash / airbag system ; it ain't gonna do ANYTHING to respond to a vertical , up& down action. It activates based on contact established by a little captured steel ball which " breaks free" from horizontal, front to back or back to front once enough force or inertia comes to an abrupt stop , it fires.

Now ,if our snout's does the same thing , it would stand to reason that he & I are experiencing some form of system shutdown due to something.
I was not winching
nor could mud resistance have factored-in on mine.
. The vertical "hop" or "drop" downward with significant force must be momentarily interrupting the Jeeps starter or battery grounds ,
I wonder if the TIPM gets jostled hard enough to flex or just super fast flex just enough to cause a blip of a loss of contact to it's mounting socket & it just power-blackouts the whole rig ?

It acts as if there is a potentiometer in the system which can detect a drop and shut off? I think we'd have read about that as a 'feature' or FCA known " thing" about the model, like how much data in in manual for the other nannies systems there is , it would be mentioned .

Plus, there is no way with all of the slickrocks and granite wedges + stumps there are out in the world's trails that me & @snout are the sole two 3.8l Jeep owners who've experienced this.
I gotta admit, I find it very strange . Made stranger by your needing to wait an hour ( :question: ) before yours'd turn over .
Hmm....pondering ....

Regardless, thanks for letting me know this. It is s bit disarming , innit it ? You go thru that , eventually you get over your top teeth impacting the lowers with enough force from the drop to echo thru your brain and make colors flash in front of your eyes only to realize your whole electrical supply has been disabled completely. WTF.
 

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well , I'll be damned , it is precisely the experience I referenced & had ( see above) . So , I read all about the crash / airbag system ; it ain't gonna do ANYTHING to respond to a vertical , up& down action. It activates based on contact established by a little captured steel ball which " breaks free" from horizontal, front to back or back to front once enough force or inertia comes to an abrupt stop , it fires.

Now ,if our snout's does the same thing , it would stand to reason that he & I are experiencing some form of system shutdown due to something.
I was not winching
nor could mud resistance have factored-in on mine.
. The vertical "hop" or "drop" downward with significant force must be momentarily interrupting the Jeeps starter or battery grounds ,
I wonder if the TIPM gets jostled hard enough to flex or just super fast flex just enough to cause a blip of a loss of contact to it's mounting socket & it just power-blackouts the whole rig ?

It acts as if there is a potentiometer in the system which can detect a drop and shut off? I think we'd have read about that as a 'feature' or FCA known " thing" about the model, like how much data in in manual for the other nannies systems there is , it would be mentioned .

Plus, there is no way with all of the slickrocks and granite wedges + stumps there are out in the world's trails that me & @snout are the sole two 3.8l Jeep owners who've experienced this.
I gotta admit, I find it very strange . Made stranger by your needing to wait an hour ( :question: ) before yours'd turn over .
Hmm....pondering ....

Regardless, thanks for letting me know this. It is s bit disarming , innit it ? You go thru that , eventually you get over your top teeth impacting the lowers with enough force from the drop to echo thru your brain and make colors flash in front of your eyes only to realize your whole electrical supply has been disabled completely. WTF.
Forgot to add, mine's a 2015.
As soon as it stops raining, I need to power wash all the mud off :(
 

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More drama today. While driving into the office, the Electrical hiccuped and again, everything went dead for about one decisecond. This repeated a few times. I got home and checked cables and grounds. I'm testing the battery and alternator at lunch.
 
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