Issue with 4lo sensor. Locker/disco not working

[Dieselcon]

My JKU crd is only 4 months young and I've had troubles when in some hard 4b'n positions when I've needed the locker. The 4LO works, however sometimes(majority of the time) the 4wd light doesn't show on the dash. Some times it works and the esp turns off and the idle goes up I can lock the diff and disconnect the swaybars, but then it will loss 4wd mode and switch off (something to do with a sensor on the transfer case i think). This is a pain as some times I get stuck because traction control cuts the power to the wheels.
Has anyone else with rubicon or offroad group had this problem, and what was the issue? Ive taken a photo of what I think is the sensor/module at fault. Any help would be appreciated. As it's been to jeep 3 times and still have the problem.


Thanks in advance
Jose

[Dieselcon]

Dropped off jeep to dealer today to replace a the 4wd module. Hope it sorts the problem out, and lucky it's under warranty. Module is worth $2700. Ouch

[wranglertj]

havent had this issue and havent heard of it either.
Let us know if this module sorts it

[qwerty]

Is the Idle up feature CRD specific?, my Rubi stays at the same revs when i go to 4lo.

[Dieselcon]

Well drama continues. Jeep installed the power trans module PTM however they also said that some other module PCM has to be changed. Will have to wait 4 weeks as it is on backorder from Germany. Bugger.

JK is still very capable as is.....so will still be going 4b'n on weekends, BLD works great. Just need to remember to turn off TC.

[SeaComms]

Damn I would have bet it was as simple as the switch to detect the lever was in 4lo (like a reverse light switch) was either fautly, not adjusted correctly or loose wire/plug.

Have they replaced the actual switch itself?

Or maybe its not just a simple switch - why on earth would you just use a switch to detect the lever position like has been done forever when you can replace all that with a convoluted and complicated computerised system

[MightyMouse]

The 4WD sensor actually generates an anolog signal depending on the TCase position. There's a selection of output voltages for selected ranges... its doccumented in the service manual.

This minimises the number of wires to the sensor.

If you ground the sensor wire the system will think the TCase is in 4low all the time, if it floating ( left high ) then the electronics think its in 2 high and obviously in between for other ranges. This is a bit of a simplification... there are actully specific voltages but you get the drift.

If there's an intermittent in the sensor system the electronics will think its come out of range thus dropping out all the things that are selected only during 4WD operation.

So could be the sensor is intemittent or its not being operated correctly by the mechanical bits of the case ( and i'm uncertain how this is actully done.... ) or its got a wiring issue or problems with electronic modules.

If i were a betting man...... i'd bet against failed elctronics and head down the more obvious and IMO feasable paths first.

The sensor side actually isn't at all complex to workwith especially if the problem is consistent - if its intermittent then its MUCH harder to diagnose properly.