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Harness issue from JL forum

Almost

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Not surprised and I'm sure you will see this become a bigger issue down the line unless it's fixed on the assembly line. I had an issue with my transmission harness in my 09 JKU. The bracket that held the harness on the firewall chafed through the harness and was throwing my trans into limp mode (no broken wires - just shorting it out). The dealer never properly diagnosed the issue and I got a free brand new transmission (@205K) under my lifetime powertrain warranty only to have the same issue came back 20K miles later. A local trans shop was able to finally find the issue after going to a different dealer and a independent shop. Jeep seems to make the harnesses super tight, but over time they often chafe due to Jeeps flexing more than most vehicles assuming you do end up hitting the dirt.
 

Sting-Gray Neutral Pres.

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I was about to write a new thread when I found this one. I suffered various issues for 3 months and it turns out this was the problem. Dealer was convinced the lift pump was going out so we got all lined up to fix that and it turned out it was this harness...I believe power to the lift pump runs through the harness so the lift pump was actually failing to deliver, it just wasn't the pump's fault. A TSB was issued earlier this week and my truck was repaired on Thursday. Good as new now. Here are all the issues that cropped up for me that this wiring harness fixed:
Service Electronic Throttle Control
Service Electronic Stability Control
ESS failure, vehicle restart required
Low fuel pressure (verified by Jeep mechanic) reducing power
And at it's worst
Transmission stuck in 3rd gear, truck enters limp mode (28 mph max)
stalling out.

This is a serious issue and folks should either get the TSB done at the dealer or follow the JL forum link to check their wiring themselves. Major headache that I was actually happy turned out to just be electrical.
 
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Sting-Gray Neutral Pres.

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Just checked my paperwork and yes that's the one. Not two weeks ago but there is some funny wording in the writeup "...also found star code for same problem s21080000014, note also found dpm front mounting bracket cam on done [sic] at welded bracket back to dpf....."
Maybe the "star code" is some sort of internal issue hilighter? Also worth noting that second part unrelated to the TSB, it sounds like a loose bracket may be an aggravating factor. Not sure what the "DPM" is though.

I think the JL forum link the OP's post may have locating info for all the DIYers out there.
 

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KW80

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Can definitely see how this could be an issue over the long term with a lot of vibration and chassis flexing. After watching the video to find the location, there are indeed a number of sharp metal tabs around the union of an exhaust/egr pipe, probably to hold a metal gasket in place for assembly. The obvious concern is a threaded wire loom sits virtually on top of one of them, so over time with vibration and movement the metal tab could cut through. Just to be safe I removed the offending tab, it serves no obvious purpose anymore. Quick and easy once you find the location. Pics below; first one is of a tab on the bottom side of the pipe (not intruding on the wire), second is of the wire loom sitting clear after removing the top metal tab, and third is the metal tab after removal.

Jeep Gladiator Harness issue from JL forum 1EA69E47-0182-4FC9-87F7-406C2DD6F2F4
Jeep Gladiator Harness issue from JL forum B1EECB75-D1FE-49E2-9BD3-FC4F75E80934
Jeep Gladiator Harness issue from JL forum 7057178C-B75D-40F1-A71F-2C4F2B054615
 
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rharr

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cool, i dug around on mine, no chafing, but can see a potential for the harness melting/rubbing on the EGR flange/tube thing that is part of the post particulate return system. I bend the tab you found down and out of the way, and poked/shoved/repositioned the harness to have some more clearance from the flange. Let's see if it stay where I put it.....

Not sure where i messed with wires is where you did. I could only get to it from underneath and don't recall seeing the flex bend pipe.
 

Wat Dog

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This was what killed my truck and left me stranded several times. It was in and out of the dealer for more than a month, at one point it was in the service dept for2 weeks. They finally discovered where the harness had rubbed through(even though I told them this was a known issue at the first visit)
Now I love my truck again. But I did add some Bluetooth battery monitors just to be safe
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