Service 4WD Message

rallydefault

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Yea, so this just happened to me.

I put my jeep into 4lo this morning to plow through the foot of snow in my driveway, then shifted back into 2hi as soon as I hit pavement. The message came on to "SERV 4WD." I drove around the block a couple times and everything seemed fine, but the message stayed.

When I came back to my driveway, I had to shift back into 4lo to get back in (yea yea I don't shovel I just go through it lol), and I noticed the indicator for 4WD hi/lo didn't show, it was just the SERV 4WD light. It still shifted, though, I could feel it and I was able to plow through again.

I have an '18 and never did check my fuses. I've never had an issue, really. Guess it's time lol I'll try the fuses, but I also have my inspection coming up so maybe I'll also ask the dealership to take a look at it. My warranty is up next month. I'm sure it's nothing major. Positive thinking.





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Tuckdawg

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My new Jeep still at dealership shop going on a month now. After trying new fixes upon consultations with "STAR engineers", still can't get SERV 4WD light to go off. I'm keeping faith with dealerships service center though. Dealership going to replace wiring harness now and see if that works. Never had this experience with another vehicle. Will follow up here when or if a fix is found. New Jeep Wrangler Willys shouldn't be in this situation.
Update - after transfer case module and wiring harness replacement (5 wks at service center) the SERV 4WD light only came on sporadically instead of on full time. I chose to keep driving to see if I could determine any kind of a trend that may cause light to appear. None was noticed so back to dealership it went. They diagnosed again and it showed "transfer case module" was the issue again and they wanted me to leave it, again. I declined. I called other area jeep dealers and found one with an experienced mechanic. Took it there and they tightened connector underneath passenger side glove compartment. Fixed finally. Jeep Cares was great through whole ordeal as well. Hopes this helps others with this same issue.
 

Ammo

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Jumped in the wife's JLUR today to run an errand and got a sway bar disconnect message, then a service 4wd message. The Wrangler is a 2019 with about 14K. We have had some snow but this was the first time the Jeep was out in it, and I knew I would need 4H. Backed out into the street and pulled the lever back. The 4H indicator did not light up and only the rear was spinning so I know it is not going into 4 wheel drive. Checked the fuses but did not find any loose. Going to crawl underneath to see if I find anything loose.

Anything else I should be looking for?

Not a good time for this to happen with the weather we are having in Texas.
 

Tuckdawg

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Jumped in the wife's JLUR today to run an errand and got a sway bar disconnect message, then a service 4wd message. The Wrangler is a 2019 with about 14K. We have had some snow but this was the first time the Jeep was out in it, and I knew I would need 4H. Backed out into the street and pulled the lever back. The 4H indicator did not light up and only the rear was spinning so I know it is not going into 4 wheel drive. Checked the fuses but did not find any loose. Going to crawl underneath to see if I find anything loose.

Anything else I should be looking for?

Not a good time for this to happen with the weather we are having in Texas.
Hi! Just based on my experience with the SERV 4WD light, loose connection was found behind glove box. Probably a simple fix but may require an experienced mechanic to pin point the problem. Good luck.
 

Ammo

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Hi! Just based on my experience with the SERV 4WD light, loose connection was found behind glove box. Probably a simple fix but may require an experienced mechanic to pin point the problem. Good luck.
I was recently back there 5o replace the in cabin air filter. I wonder if I could have done something?
 

mwilk012

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Hi! Just based on my experience with the SERV 4WD light, loose connection was found behind glove box. Probably a simple fix but may require an experienced mechanic to pin point the problem. Good luck.
Just FYI, that’s a really bad diagnostic tactic. That’s like saying “when I had the check engine light problem”.

if it’s under warranty, take it in. If you happen to have a programmer, disable the sway bar disconnect and try again.
 

danzy55

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Message “Service 4WD” just popped up on my JL Sahara dashboard.

Going to call dealership Monday morning.
Not even 2,000 miles on it yet. Does anyone know what may have caused this alert?
Well I have had pop up 4 times on my 2020 Gladiator Rubicon, they ended up having to completely re-wire my entire Jeep front to back. Kicker is after that it still came on all at 28,000 miles so the Gladiator went bye bye! Good luck, I doubt its this extreme but get it fixed and fixed right.
 

Tuckdawg

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Just FYI, that’s a really bad diagnostic tactic. That’s like saying “when I had the check engine light problem”.

if it’s under warranty, take it in. If you happen to have a programmer, disable the sway bar disconnect and try again.
Was under warranty and SERV 4WD light was on because of loose connection as diagnosed at Jeep dealership service department. Yes absolutely if it's under warranty take it in.
 

Ammo

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Dealer found the issue for the error code in my case. Something chewed through some wires down by the transfer case, probably a rat.

The cold temps we had in TX had a rat seeking warmer shelter in the garage. Rat poison and traps have been set for that little bastard.
 

MrMischief

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Backed out into the street and pulled the lever back. The 4H indicator did not light up and only the rear was spinning so I know it is not going into 4 wheel drive.
I thought the JL was still using a mechanical lever, so I would think that if you pulled it into 4 high the front drive shaft should be engaged. Can the FAD prevent both front tires from turning even if the transfer case is in 4 high?
 

eck

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Can the FAD prevent both front tires from turning even if the transfer case is in 4 high?
If the FAD doesn't engage the axle for some reason, then it's not much different from lifting the passenger wheel in the air with an open diff. The driveshaft will turn the ring and pinion but it's only going to spin the passenger inner shaft. Neither tire will turn.
 

Ammo

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I thought the JL was still using a mechanical lever, so I would think that if you pulled it into 4 high the front drive shaft should be engaged. Can the FAD prevent both front tires from turning even if the transfer case is in 4 high?
Shifting into must only engag the transfer case to lock in the front driveshaft but the FAD was not getting the proper signal so it never engaged the front axle.

I'm guessing. Dont know for sure.
 

mwilk012

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Shifting into must only engag the transfer case to lock in the front driveshaft but the FAD was not getting the proper signal so it never engaged the front axle.

I'm guessing. Dont know for sure.
Correct.
 

Kurt0

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Update - after transfer case module and wiring harness replacement (5 wks at service center) the SERV 4WD light only came on sporadically instead of on full time. I chose to keep driving to see if I could determine any kind of a trend that may cause light to appear. None was noticed so back to dealership it went. They diagnosed again and it showed "transfer case module" was the issue again and they wanted me to leave it, again. I declined. I called other area jeep dealers and found one with an experienced mechanic. Took it there and they tightened connector underneath passenger side glove compartment. Fixed finally. Jeep Cares was great through whole ordeal as well. Hopes this helps others with this same issue.
what was this connector? Can you elaborate?
 

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