Downhill : Transfer case , check engine light, service 4WD

[scruch]

Hi all,

Looking for some input after a situation today.

Vehicle: Jeep Wrangler JLU 2.0T (modified, heavier than stock)

Scenario:
I was driving downhill (~10% slope) for about 4 km with a fully loaded car, with roof box and whole family… very very heavy . I stayed in 2H and used 2nd gear for engine braking. RPM was around 4000 for most of the descent.

At the end of the downhill:

• the 2H light started blinking and then went completely off. No signal from transfer case on uconnect or dash
• “Service 4WD” message came on
• check engine light come on
• (Screenshot attached)

It happened after the discend. After a few kn on plain …I stopped. After a short wait and restart:

• transfer case warning disappeared
• 2H light returned to normal

However:

• Check Engine Light is still ON

Current status:

• Jeep drives perfectly normal
• no loss of power
• no noise or vibration
• Transfer case works as normal

My questions:

1. Could this be a transfer case overheating / overload protection event?
2. Is it normal that a CEL remains after this kind of situation?
3. Any known codes related to high RPM engine braking on the 2.0T?
4. Should I be concerned or just monitor and wait for it to clear?

Additional note:
Transfer case oil was recentlyy changed, so also wondering if that could play a role.

Appreciate any insights or similar experiences.
Also on how to reset it

Thanks!

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[EbyCreek]

I assume you don't have a Tazer or OBD II reader? Most parts stores should be able to read your check engine code for free.

 

[Andy@AAV]

Sounds like you may have had a heat issue on the transfer case or transmission. I don't think you can check the T-case temp on the dash, but I may be wrong. Either way a solid check engine light is a saved code that usually indicates something exceeded the programed limits but is not currently occurring.

Get someone to read the code and clear it. Maybe check the color/smell of the T-case fluid to see if its black or smells burned (you will know if you smell it, it's awful).

 

[scruch]

I assume you don't have a Tazer or OBD II reader? Most parts stores should be able to read your check engine code for free.

Very good idea. I forgot i can read with tazer.
I did but the issue is that errors code where never cleaned out.
So i resetted it now and see if somethjng comes back.

In any case these are the code the tazer list:

• ORC: 1 code
• B210A-00

• RFH: 2 codes
• B21DD-84
• P2199-16

• Another displayed code:
• C1403-92
U1440


Thanks

 

[roaniecowpony]

I googled U1440 and found this... https://www.jeepgladiatorforum.com/forum/threads/u1440-dtc-anybody-have-this.49973/

 

[roaniecowpony]

B210A-00 has to do with low voltage. It looking to me like you either have a bad aux battery or a wiring problem.

https://www.google.com/search?q=jee...YAIAA&sclient=mobile-gws-wiz-serp#lfId=ChxjMe

 

[scruch]

Thanks a lot all
I believe that many of these errors where there since years. I did a lot of battery work , including the exclusion of aux battery and never resetted obd.
Lets see if i get a code again after reset.

I was wondering if there is any correlation by heavy transfer case usage and those errors
If there is any correlation of transfer case heat and connector eletrical issues like the one i had

Because it is a luttle bit suspicious that i got eletrical error exaftky when i stress transfer case

 

[roaniecowpony]

Chasing electrical gremlins is never fun. There's some very knowledgeable people about the bus systems on this forum. Possibly some of them will find this thread and lend a hand.

 

[scruch]

Yesterday I came down from one of the steepest tracks in Italy, the alpine route from San Glisente.

.. It was a very long and demanding mountain descent, roughly 20 km up and down, with an average gradient that is already extreme and several sections getting beyond 30%. It is the kind of descent where you are constantly managing speed, heat, and traction, with almost little margin for error. Definitely not just a casual trail, .. especially for a truck this weight.

Overall, the Jeep handled it well. I used a mix of Hill Descent Control on the steepest pitches, especially where the slope was close to 30%, and a lot of low-range 4x4 engine braking to keep the speed under control. So from a drivetrain and transfer case point of view, everything actually worked fine.

Despite the descent being much more demanding than the one that originally triggered this post, I had no transfer case errors, no warnings, and no related issues at all, even though the whole system was clearly under much more stress than before.

The only really strange behavior happened with the fuel gauge. At one point during the descent, the Jeep suddenly stopped reporting fuel correctly. The level dropped very quickly into reserve and then even below, basically showing the tank as empty. I was honestly worried that I had somehow lost fuel or that I was about to remain stranded on the mountain during night.

Because of that, I increased my pace on the way down, as I was afraid of getting stuck up there late in the day. As a result, the brakes got very hot. Still, I made it all the way down without any actual mechanical issue. But breaks where overheating clearly.

Once I reached flat ground, I restarted the car and the fuel indicator immediately returned to normal, showing that I still had around 30 liters left in the tank.

So in the end, the transfer case was completely fine, even under a much more serious downhill load. But once again, on a steep descent, the Jeep showed a very concerning fuel-reading issue. I have to admit I am getting a bit frustrated with the reliability of this car when going downhill…. Its full
Of suzuki , toyotas , doing similar things with no issue at all ..

Few footage
:

 

[Grayhound]

Happy to hear the t case didn’t give any errors. I’m not too surprised at the fuel readings with a 30% and 17%sustained gradient. That is steep.
The mountains of Italy look beautiful in your video!

 

[flick2614]

Clear all codes and see what comes back. Sounds like you have too many historical codes to diagnose.

 

[THAW]

The only really strange behavior happened with the fuel gauge. At one point during the descent, the Jeep suddenly stopped reporting fuel correctly. The level dropped very quickly into reserve and then even below, basically showing the tank as empty. I was honestly worried that I had somehow lost fuel or that I was about to remain stranded on the mountain during night.

Normal.

If the tank is less than mostly full, the fuel sender float shifts a lot on steep inclines and declines causing the tank level reading to be high and low, respectively; the fuel sender data is averaged over time, so there is a delay before the fuel gauge shows the change caused by a sustained grade.

 

[THAW]

I don't think you can check the T-case temp on the dash, but I may be wrong.

Definitely can't check transfer case temp on the dash. I looked into it a bit to see if it can be monitored in JScan, and based on not finding any PIDs plus information I found online, JL transfer cases don't have a temperature sensor.

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