Service 4WD Lights

[j_stew762]

I purchased a stock '20 JLURD in Jan. No lift, 35's with 21k miles. In April I put on a 2.5 inch MC GC, Rocksport's, front drive shaft, and 37's. Took it to Axleboy in Missouri and they gave it a once over, helped me balance the tires (something DT couldn't figure out after two trips) and everything has been great. Now for the problems...

During the past 6 weeks or so, I've noticed the 2H light on the dash would flicker, with no rhythm, I have determined it would flicker as I went over bumps in the road (leading me to believe it's a bad wire, or ground?). Eventually the problem grew into the Service 4wd warning, which also disabled the sway bar disconnect feature. I can almost make the Service 4wd feature appear by reversing up my driveway (slight incline, 7-8 degree angle maybe, 4-5ft of rise over 35ft.). So I made the warning activate so I could plug in my splitter/vLinkerMC+ and tap into my Jscan. The following break down is what I have.

Anti Lock Brakes
U0403-00 implausible date received from transfer case
Drive Train Control
C1403-11 transfer case range position sensor - circuit short to ground
Driver Assistance System
C2227-00 abs disabled ecu
U0403-00 "same msg as above"
C2226-00 tcm disabled ecu
Park Assist
U0403-00 "same as above"
Sway Bar
U0403-00 "same as above"

I'm familiar with the fuses under the hood, and pushing them all down to make sure i have good contact, that's been done. I checked the abs wiring/speed sensors to each wheel and cant find a bad connector, or frayed wire that would cause the 2H light to flicker over bumps/when braking/when reversing up a hill, as previously described.

I'm familiar with after installing a lift, the linkage for the 4wd shifter may need to be adjusted.....may go down that rabbit hole today. I've also read that the transfer case switch may need to be replaced. I'm just not sure which it is based on the current symptoms of the Jeep, and it only having started after the lift was installed (case in point I bought in in Jan '23, stock with 35s, put 3-4k miles on it, no issues at all when lift was put on in Apr '23).

The 4wd still works, even when the service 4wd light is on, in both 4H and 4L. The only feature that's unavailable is the sway bar disconnect.

I have a trip to Colorado in a month, with a lot of trails on the list, and would like to get this fixed before I leave. Keep in mind, I trust dealerships like I trust the federal government....

Before I dive into this, what are some recommendations from the forum experts?

Sponsored

 

[At Risk Ute]

Not a fan of dealers either, but I’d have a friendly one look since it’s under warranty.

If 4H, 4L, and assuming your lockers also still work, hedge your bets by installing some sway bar discos.

 

[Barney392]

I purchased a stock '20 JLURD in Jan. No lift, 35's with 21k miles. In April I put on a 2.5 inch MC GC, Rocksport's, front drive shaft, and 37's. Took it to Axleboy in Missouri and they gave it a once over, helped me balance the tires (something DT couldn't figure out after two trips) and everything has been great. NO for the problems...

During the past 6 weeks or so, I've noticed the 2H light on the dash would flicker, with no rhythm, I have determined it would flicker as I went over bumps in the road (leading me to believe it's a bad wire, or ground?). Eventually the problem grew into the Service 4wd warning, which also disabled the sway bar disconnect feature. I can almost make the Service 4wd feature appear by reversing up my driveway (slight incline, 7-8 degree angle maybe, 4-5ft of rise over 35ft.). So I made the warning activate so I could plug in my splitter/vLinkerMC+ and tap into my Jscan. The following break down is what I have.

Anti Lock Brakes
U0403-00 implausible date received from transfer case
Drive Train Control
C1403-11 transfer case range position sensor - circuit short to ground
Driver Assistance System
C2227-00 abs disabled ecu
U0403-00 "same msg as above"
C2226-00 tcm disabled ecu
Park Assist
U0403-00 "same as above"
Sway Bar
U0403-00 "same as above"

I'm familiar with the fuses under the hood, and pushing them all down to make sure i have good contact, that's been done. I checked the abs wiring/speed sensors to each wheel and cant find a bad connector, or frayed wire that would cause the 2H light to flicker over bumps/when braking/when reversing up a hill, as previously described.

I'm familiar with after installing a lift, the linkage for the 4wd shifter may need to be adjusted.....may go down that rabbit hole today. I've also read that the transfer case switch may need to be replaced. I'm just not sure which it is based on the current symptoms of the Jeep, and it only having started after the lift was installed (case in point I bought in in Jan '23, stock with 35s, put 3-4k miles on it, no issues at all when lift was put on in Apr '23).

The 4wd still works, even when the service 4wd light is on, in both 4H and 4L. The only feature that's unavailable is the sway bar disconnect.

I have a trip to Colorado in a month, with a lot of trails on the list, and would like to get this fixed before I leave. Keep in mind, I trust dealerships like I trust the federal government....

Before I dive into this, what are some recommendations from the forum experts?

I've heard of problems with the wiring going to the sway bar disconnect are rubbing on something and wearing through causing a short circuit. You might stick your head under the front of the Jeep and trace the wiring from the disconnect back a few feet and see if there are any problems.

 

[j_stew762]

Not a fan of dealers either, but I’d have a friendly one look since it’s under warranty.

If 4H, 4L, and assuming your lockers also still work, hedge your bets by installing some sway bar discos.

I have an appt with my local dealer next week but based on my conversation with them in person today, I'm not convinced they're gonna be any help. My appt is to have a tech ride with me so I can show him the flicker, and "how to" make the service 4wd msg appear.

Side note, I tore into the center console to check the 13mm nut that adjusts the transfer case shifter. It appears to be adjusted properly based on what others have posted. Also, ground location 916A (pass side, under rear seat) was grounded properly. This location was listed in another thread as sharing a ground with the transfer case and abs wiring.

 

[speedymart]

C1403-11 transfer case range position sensor - circuit short to ground

Boggles my mind people see this and start asking about the disconnects? Your range sensor is either failing, the connector isn't fit correctly, or there's some damage in the wiring between the DTCM and the sensor. This DTC will cause all of your symptoms. The short to ground indicates the T314 circuit is either rubbing ground somewhere or the DTCM/Sensor is shorting to ground. I'd strongly suspect wiring damage along the T314 circuit somewhere.

That being said, inspect the harness by the EGR tube/valve gasket to see if it's rubbing through. If it is just position the harness away. We've seen this issue before

 

[j_stew762]

C1403-11 transfer case range position sensor - circuit short to ground

Boggles my mind people see this and start asking about the disconnects? Your range sensor is either failing, the connector isn't fit correctly, or there's some damage in the wiring between the DTCM and the sensor. This DTC will cause all of your symptoms. The short to ground indicates the T314 circuit is either rubbing ground somewhere or the DTCM/Sensor is shorting to ground. I'd strongly suspect wiring damage along the T314 circuit somewhere.

That being said, inspect the harness by the EGR tube/valve gasket to see if it's rubbing through. If it is just position the harness away. We've seen this issue before

Fairly confident my problem is not a sway bar disconnect issue.

My biggest tell right now is the 2H indicator on the dash flickering when I hit a bump, or brake (weight of vehicle rolling forward), as well as backing up a hill/incline (again weight of vehicle pushed forward), with this issue somehow being induced post lift kit. A stretched wire of some sort somewhere seems to be the cause. Lord only knows where it is or how to find it at this point.

What's the best way to get to the wiring for the transfer case switch? I've located the transfer case switch, and can barely see the two wires coming out of the black plug that sits atop of it.....not seeing anything glaring.

 

[speedymart]

Fairly confident my problem is not a sway bar disconnect issue.

My biggest tell right now is the 2H indicator on the dash flickering when I hit a bump, or brake (weight of vehicle rolling forward), as well as backing up a hill/incline (again weight of vehicle pushed forward), with this issue somehow being induced post lift kit. A stretched wire of some sort somewhere seems to be the cause. Lord only knows where it is or how to find it at this point.

What's the best way to get to the wiring for the transfer case switch? I've located the transfer case switch, and can barely see the two wires coming out of the black plug that sits atop of it.....not seeing anything glaring.

Follow the harness. Eventually you'll find it runs along the EGR tube/valve. There's been reports of the gasket that sticks out between them can rub against the harness resulting in random short-to-ground issues. This leads to the exact symptoms you're describing.

 

[j_stew762]

Follow the harness. Eventually you'll find it runs along the EGR tube/valve. There's been reports of the gasket that sticks out between them can rub against the harness resulting in random short-to-ground issues. This leads to the exact symptoms you're describing.

Followed it along the transfer case to the transmission where it joins a large harness. Followed that near the EGR tube, and located a few metal tabs from the gasket that seem to be rubbing a hole in the wiring harness sleeve/loom.

Unplugged the two large connectors from the pass firewall to create some slack but there’s still not enough slack to pull it down and inspect/repair.

 

[speedymart]

You shouldn't need to actually repair it, it's a super tiny break in the insolation. Use zip ties or something similar to pull the harness away from the tube so it can't rub anymore. Good shit finding it

 

[j_stew762]

You shouldn't need to actually repair it, it's a super tiny break in the insolation. Use zip ties or something similar to pull the harness away from the tube so it can't rub anymore. Good shit finding it

I actually pulled the harness back and tucked it between the two heatshield’s to the left of my hand in the picture. I was able to wedge it down in there, to keep it away from the egr gasket, and I dont see it popping back out at this point.

I took it for a quick test run last night, and backed into my driveway trying to get the service 4wd message to activate and couldnt get it to happen.

With it shorting out though I gotta believe there is, at minimum, an exposed wire to some extent. Long term, I’ll take a look at dropping the tube and exhaust to access the harness better.

I very likely would not have found it without your help though. Prime example of why this forum exists and how a few like minded people can find a “fix” to a problem.

 

[j_stew762]

3-4 days later and I still cant get the service 4wd message to pop back up. I’d say it’s safe to say I’ve located my issue, being the wiring harness that was rubbing on the metal fins on the egr tube gasket.

Food for thought for others experiencing the same thing.

 

[GMONEY]

3-4 days later and I still cant get the service 4wd message to pop back up. I’d say it’s safe to say I’ve located my issue, being the wiring harness that was rubbing on the metal fins on the egr tube gasket.

Food for thought for others experiencing the same thing.

Well I know what rabbit hole I'll be going down tomorrow morning.

Thanks for the info.

 

[IanNubbit]

Basically ignore every code except range sensor short to ground. Seen it a few time now. All 3 times it was the XY430A connector. Thats the large connector in the right front wheel well. Body side, unplug and make sure theres no corrosion or water. Make sure the inner pin retainer is fully seated, and put a small amount of dialectric grease on the femal side. Reconnect, clear codes ans try it out. It could of course be other things, but this has been my experience

edit, oh its a diesel, yeah that EGR tubewrecks that harness all the time lol

 

[GtX]

I have this exact same issue. I noticed the 2H would flicker about weeks ago and have been trying to purposefully replicate it. Have determined it happens when decelerating on steep grades using engine breaking. Today, I reversed into a parking spot and got the Serv 4WD light, swaybar, etc.

Is this picture taken from the ground looking up in the vicinity of the passenger front tire?

Followed it along the transfer case to the transmission where it joins a large harness. Followed that near the EGR tube, and located a few metal tabs from the gasket that seem to be rubbing a hole in the wiring harness sleeve/loom.

Unplugged the two large connectors from the pass firewall to create some slack but there’s still not enough slack to pull it down and inspect/repair.

Sponsored