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  Topic Review (Newest First)
10-06-2019 02:05 PM
Avs I picked up a 2006 wk 5.7l overland not too long ago with 136k miles. All of a sudden I get the “service 4wd system” on the dash while pulling out of my driveway. When I shifted from reverse to drive there’s a long clunking noise then the engine immediately shut off. I did the start and shut off a few times and the problem seem to went away. I also took it for a 30 min drive and the drive seems to drive fine and no clunking whatsoever when shifted from park, reverse, neutral, drive etc.
So I went on the fca recall website to check the vin and both the n23 and p73 recalls were completed. From what I understand, I should be only getting this error message when I want to activate the 4wd lo. Does this recall affect the overland model as well with the front electronic diff ever tho I didn’t activate the 4wd lo? From what I gather, some people are able fix this issue by going back to the pre-flashed fdcm and some need to replace the transfercase actuator. Sorry a n00b a bit late to this fiasco. TIA!
02-02-2019 12:40 PM
JeepBrian Hi Jeff:
What fixed your problem?
As I see it:
The only input to the transfer case is the shift motor. The motor moves and can be locked. Its position controls shift position 4H, N, and 4L along with torque ratio between front and back drive shafts. Both axles have their torque ratio between left and right controlled by clutch application. The clutch application is controlled with a pulse with modulated voltage. With this system, torque can be applied in any ratio to all 4 wheels independently.
The only relevant intelligence the system receives is wheel and transmission output angular velocities.
Process this and produce torque to the most needed wheel.
The voltages that I supplied were actual ones read at the final drive controller during road testing. I used the 5 Volt common as zero reference.
I hope this all helps.
12-21-2018 11:41 AM
Jeff2010 Brian, Will try get hold of a Blue Driver scanner to watch the feed back signal voltages. Still a lot to learn about pulse width modulated voltage signals and how they work in a DC motor system to give proportional clamping on the clutches. Are you saying 4 high lock position is a different radial location and it varies in angle for 0 to 100% lock up or is there another electrical connection to the hydraulic control of the clutches? Are we mixing up the control of front and rear ELSD's with control of the centre diff locking clutches (which I thought were mechanically controlled by the actuator rotation?)
Attached is a picture of the wear on the position sensor carbon tracks. Your voltages don't tally with those in the manual. Want to build up a complete table with max and min voltages and angles of rotation both pre and post N23/P73. It is now working without the new Dorman actuator but I suspect it has more accurate position feed back but I could be wrong.

No explanation yet for mysterious shift into low ratio a few months ago or exact relationship of my issues with FDCM reprogramming but I think the actuator position monitor is just not accurate enough to sense difference between AWD and 4WD hi lock positions and reset actuator back to AWD (unlocked centre diff) quick enough or reliably enough. New aftermarket actuator may improve this. These 2 positions appear to be just 10 deg and maybe 0.5 volts apart – again no data in manual for 4WD hi Lock but I know AWD unlock feed back voltage is stated in the manual as between 0.45 and 0.55 Volts (pre recall).
Rumour has it that reprogram tightens up the tolerances for feed back of the shift positions in the transfer case so if the actuator lands outside the new tolerances it tries to shift again to where it does meet the new tolerance. If the actuator brake is not fit or sticking or the accuracy of resistor not up to it, it could hunt about forever (maybe this caused the wear I noticed in the first 10deg range of motion).
If I buy a scanner with real time monitoring I can watch these feed back signals on the fly.

It is fixed and now working reliably but I am not totally sure why. Will get to the bottom of it eventually. An interesting puzzle for the Christmas holidays!

Merry Christmas and a happy and prosperous New Year!
12-21-2018 11:14 AM
Jeff2010 Gents,
Brian thanks for the updated info above. See below for what I gleaned from the maintenance manual. Would be great to continue this conversation. I was about to make position map of the actuator positions building on your and CMDRJIM's work in but I stumbled on a simpler solution quite by accident. I found out why it was getting the spurious shift inputs! More to come on this. I will still need to either go back to pre N23 software and install the new actuator but for now it is working.
Sorry if I am misleading some readers on the comparative mileage with the same engine in the Merc ML but I had the pleasure of driving one with the 3.0 L V6 turbo diesel (maybe a bit newer 2010 ish and a UK new vehicle) to Glasgow recently and while cruising at 60 to 70mph on a flat road the car was averaging 40mpg as per the dash readout, but we have bigger gallons than you but still quite a significant improvement over the 30 or so mpg (UK imp G) that the Jeep can achieve in its best condition. Your standard highway tests do return a bit less than what I would call average cruising economy and US models may also be sightly less efficient due to your stricter emissions regulations (I have not completely figured out why sacrificing mpg is better for the environment but I get it is to with reducing some harmful exhaust components NO's, Co and unburnt fuel etc and not just reducing the amount of fuel used).

You may be relieved to know I have fixed my problem with the binding drive train in the Jeep. Its like a new car. I have full 4wd capability and no compromises.

I suspect this problem has been with the car for the last 2 years and the previous owner did not notice or repair it (neither did the Jeep dealer who sold it to him in late 2015) and this may account for the worn front tyres and the fact it has done so little mileage over the past 3 years - no one would want to drive it. It is only when it got so massively worse after the recall work that I was forced to get into the detail of the fault (since the dealer and Jeep would not help).

It's a bit of a Christmas miracle and the car is back from 16mpg (US gal as per DIC on dash) to 28mpg (30 ish UK mpg) on a trip so very happy and no more thumping drive shaft episodes. When I get a chance I will write it up with photos for the benefit of readers.

No so much of a conspiracy as first though just a combination of poor design, quality control and bad programming in the FDCM (maybe because of the N23/P73 recall) software causing unforeseen interactions and frankly still unexplainable interactions between the rear diff and the centre diff but I am reading up to see if I can find the link.
Does anyone know if the rear axle has sensors which can measure or calculate torque to each rear wheel? The maintenance manual mentions abs sensor disconnection when removing the diff nugget but as far as I can see it only has abs wheel speed sensors at the outer wheel bearing/hub and just a 2 wire connection to the elsd solenoid in the nugget. It is possible it makes a comparison left to right to calculate twist if speed pulses get out of sync. I only have a copy of the earlier 2005 to 2008 manual so it maybe inaccurate for my model - 2010. I did find quite a few inaccuracies and cut and pastes from earlier models.
If the elsd clutches and centre diff clutches are mechanically/hydraulically disengaged, as they are supposed to be in normal driving on a flat straight road or even in moderate corners and manoeuvring, then there is no need I can see for adding anti friction additives. These may just stop it working when you want it to bind up. The programming in the FDCM is supposed to prevent binding for maximum economy when in normal driving. Try driving a ford ranger (my other truck used for towing the competition 4x4 trialer) with the transfer case locked in high ratio on the road and see what it does to performance and fuel economy.

Also still looking to find a plot of the radial movements (measured angles) of the transfer case actuator and the voltage feedback limits for the various actuator positions, both pre and post N23 updates. manual was not much help and only had voltage feedback limits for AWD unlocked (0.45 to 0.55V) and 4WD low diff locked(4.19 to 4.35V), I am guessing due to age of manual these are pre N23 update.

Merry Christmas to all and I hope to post a comprehensive report in the new year.
12-18-2018 09:40 PM
JeepBrian Here is what I have to offer:

Proper sensor voltages:
4WH 2.82 Volts
-My Guess: When in 4WH the voltage can vary to apply clutch pressure in the case when slippage is detected; > 2.82 Volts
N 1.94 Volts
4WL 0.84 Volts
-The voltage output tolerance is quite tight at plus or minus 2%
-My Guess: The differential clutches are applied using a pulse width modulated voltage signal from the Final Drive Controller. The duty cycle is calculated using wheel slip information. The inductance of the coils smooths the current and produces a smooth proportional clutch application.
Shift Motor System Wiring:
Shift Motor GN – 1 – BR - C2-15 – 5V Signal Supply
Shift Motor BN – 2 – YL/LG - C2-05 – Input Signal
Shift Motor GY – 3 – BR/LG - C2-16 – Signal Return (Grounded)
Shift Motor BK – 4 – YL/BR - C1-13 - Motor
Shift Motor RD – 5 – YL/GY - C1-12 - Motor
Shift Motor OR – 6 – DG/YL – C1-14 - Lock (+12 V Supply)
Shift Motor YL – 7 – YL/TN - C1-17 - Lock (Ground to Lock)
The lock is a lock for the shift actuator only.
About the Sensor Schematic; Attached file
-Two of the fixed resistors provide the capability of fault detection on the signal circuit; grounded or high (5 Volts).
-The other fixed resistor prevents possible grounding of the sensor’s output.
-Assuming the final drive controller's input resistance is quite high, it should be possible to calculate angle vs voltage. This should give you the troubled area; where the carbon is polished.
If you have a diagnostic tool you can watch the sensor signal and see what it is doing.


12-17-2018 08:30 AM
Brit30-06 Hi Jeff
There should be no friction modifiers added to the transfer case fluid. Diffs yes with qd2 but NOT transfer case. Which fluid have you put in?
12-17-2018 07:08 AM
Jeff2010 Fitted the new tires and guess what - absolutely no change! Centre diff locked with in 400m of me driving out of my yard and again 2 more times in the 2 mile round trip.
I am beginning to think this is a fairly common issue and all the BS about fluids and friction modifiers is just that - BS! they are again trying to cover up for the fact that the center diff locks randomly and adding a friction modifier just allows the plates to slip when in fact they should be mechanically disengaged.
Ever wondered why the 3.0L CRD engine only gets 26 miles per imp gallon in this vehicle when the same engine gets 40mpg (highway) in the Mercedes MIL (same shape weight and tires).
New Actuator arrives later this week. Fingers crossed!
12-17-2018 02:28 AM
Jeff2010 sorry that should have read "tightened up the tolerances to a point where it can't work" Maybe th eposition feed back provided by the position sensor potentiometer is just not accurate enough.
12-17-2018 02:26 AM
Jeff2010 Up in Aberdeenshire. Would be good to try and collate the problems UK and Canadian users of this 3.0 CRD WK model have been having. Might have also to go search for a pre N23 reflash FDCM if they have tightened up tollerances to a point where it can work. Would like to know from anyone who may know the locations of the various functions, diff lock, neutral, low 4 etc so I can make a radial map and and maybe work the box manually with the motor off and see if I can simulate the difflock problem. Not sure yet if it is automatically generated by differential drive shaft speeds or if it is the actuator causing the problem. I did put one of the worntyres on opposite corners to try rule this out but if electronic it may be looking at wheel speeds not shaft speeds (if hydro mechanical). Are there any other electrical connections to the transfer case? Will read up on the NV 245 function and get to the bottom of it. 10 more posts to go before I can send photos and PM the folk I have seen reporting center diff lock symptoms. but please PM me if you have similar problems.
12-15-2018 02:44 PM
Brit30-06 Hi Jeff
I feel your pain mate. Trying to get a tricky fault diagnosed can be a nightmare. If Arnold Shark have not been a Jeep dealer long then they will be clueless about our WH model. A lot were Fiat dealers and took Jeep on by default.
Have you an independent jeep specialist local to you?
Only time my transfer case has tried to lock on its own was when I had an abs sensor out. Had warning lights on dash then though.
Where in uk are you?
12-15-2018 01:11 PM
Jeff2010 Forgot to add, new tires getting fitted Monday and have ordered a Dorman actuator. Will post on which of the 2 solves the issue.
Then decide if this is N23 related and if to push Jeep for reimbursement for actuator and costs. They are playing dumb
12-15-2018 01:09 PM
Jeff2010 Hi All,
Pulled the transfer case actuator as per JeepBrian's work sheet and tested the printed position sensor board. No faults found but did notice that there appears to be an area of about 10deg where the actuator has been cycling back and forth and has worn and polished a bit of the carbon linear resistor. Not sure if it is getting bad inputs from wheel speed sensors (no codes but slightly different wear on front tires versus rear) causing it to cycle or it is giving bad outputs causing the FDCM to select the diff lock position??
Can't pot photos yet as newbie but will update with pictures as soon as \i can. Can't do PM's yet but maybe if you are reading can Penguin_Jeep get in touch with me by PM.
12-13-2018 03:58 AM
Originally Posted by Penguin_Jeep View Post
I've not had mine flashed - the stop the transmission binding the axles together after a short stop (turning off for fuel for example) - instead I pulled the fuse.
Not the FCDM fuse but the one for the E'diffs right next to it...
Do you get the lockup?

Mine is the 2005 3.0 CRD, WH
This is my first post and I know this is an old thread but you are the first person I have seen with a UK 3.0 crd with the drive shaft binding issue. I have exactly the same problem on my 2010 WH Gr Ch. Did you get your issue resolved and how. Local Jeep dealer Arnold Clark has been useless as has Jeep Customer care - playing dumb.

Any help appreciated. No codes and no dic "service 4WD". Shifting into low still works and i use this to unlock the center diff but since I took the car to the dealer 3 weeks ago I can't move it without the centre diff locking and drive shafts start thumping. Engage 4WD low and disengage and the problem goes away for a bit. Explained all this to dealer and Customer Service and they say I have to pay for re-diagnosis - even though they had the car for the N23/P73 recall work and were told of the binding issue.

Just away to pull the actuator and do Jeep Brian's diagnosis and maybe solder repair on position sensor if faulty.
It did shift once into 4wd low by itself when we were driving off a ferry ramp about 4 months ago.

Any help greatly appreciated
10-06-2018 01:18 PM
JeepBrian I only had the violent behavior before any software updates.
10-01-2018 03:51 PM
suzieque jeepbrian, are you saying your jeep would randomly shift into 4lo while driving after doing the n23 recall?
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