Service 4wd system message help! - JeepForum.com
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post #1 of 26 Old 09-22-2017, 07:42 PM Thread Starter
motorhead86
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Service 4wd system message help!

Let me start by saying I have dug through thread after thread and none of them seem to have an answer to the issue even though so many people have been plagued with this issue. Most end up taking it to a dealer and tossing money at the problem and hoping for a fix. But thats not something I am interested in doing. I have posted on this issue on another Jeep forum but haven't got much traffic on my post so I was hoping I might have beeter luck here. I am going to copy and paste all my posts from the other forum over here so you can all see what the issue is exactly and what I have done so far to try and fix it. Hopefully you guys have an idea of what else could be going on. Thanks in advance for the help!.


2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #2 of 26 Old 09-22-2017, 07:43 PM Thread Starter
motorhead86
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Here is a copy of my first post on the issue and all the posts that follow this post will be in order of the updates on things I have done to troubleshoot the problem.

My wife has a 05 Grand Cherokee Limited with the 5.7 Hemi 105,000 miles. Yesterday she hopped in the Jeep and started it and immediately a message popped up on the evic saying "service 4wd system". The Jeep still drove the same as always, no funny out of the norm noises either. I tried engaging 4low but it will no longer engage. When I pull on the T handle it just flashes the "service 4wd system" message again.

This message stays on the dash unless you push the step button on the center console. I have no other lights on (no traction control or abs or brake lights or anything like that).

The Jeep had the FDCM recall update done on it about a year or so ago aswell.

I have dug through thread after thread after thread and can't find exactly what the problem could be. I have tried pulling fuses #25 as some have suggested and reinstalling it but it made no difference.

Also it has not rained so I don't believe it to be a moisture issue. I find it strange that we havent had this problem and then all of a sudden on the first start up of the day it randomly now has this message.

The ONLY thing I could think of is....I seen some make mention of a weak battery could cause it?. Her Jeep has died before after listening to the radio for 15-20 minutes so I guess you could say the battery isnt exactly 100% but I have tested it with a toaster box and it tested good. And the Jeep starts up no problem also. So I am not sure if that would be the problem.

Hopefully someone can steer me in the right direction here on what my next step should be. I apologize for creating a thread when I know this topic has been gone over quite a few times but like I have said I have dug through threads for hours and haven't found what I am looking for and most of the threads I did found went way off topic or it was folks throwing thousands of dollars at it at a dealership hoping something would fix it. And that is not something I am willing to do. I do all my own work and just need guidance as to where I should start looking. Thanks in advance.
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2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #3 of 26 Old 09-22-2017, 07:44 PM Thread Starter
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Also in May of 2013 it had the N23 recall service performed. In July 2014 it had the P41 recall service performed. And in May of 2015 it had the P73 recall service performed.

Today I load tested the battery . Without load it tested out to around 12.2ish volts and under load it dropped to about 11.2-11.5 volts. I also unhooked the battery and let the system discharge and reconnected it and the service 4wd system message immediately popped back up.

Ran the on board diagnostics and got no codes. Decided to take it into advance auto parts and have them hook up their scanner to it even thought I was pretty certain they wouldn't be able to tell me anything. And just as suspected they said they were getting no codes aswell. The kid behind the counter suggested I try buying all new wheel bearings and see if that fixes it lol. I'm not interested in throwing money at it hoping for a fix. I am looking for educated guess and for what the mass's found the issue to be on their Jeep so I have atleast a good idea of where to focus my attention.

Any help would be greatly appreciated.

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #4 of 26 Old 09-22-2017, 07:44 PM Thread Starter
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Today I tried just about everything I could think of and still no luck!.

I had the battery unhooked for hours. I had it on charger even though it tested out fine. I checked every fuse. I pulled the rear seat and checked the ohm resistance and continuity to the wires going to the front and rear differential actuators. I also got under the jeep and checked the readings at the actuators themselves and everything was good. I pulled the harness off of the Transfer case motor and thought I had found the problem when I found one pin that had corrosion on it. cleaned the corrosion up and dielectric greased everything but the problem persisted.

I found that neutral still worked and it was just the 4lo that was not working.

I pulled the transfercase motor off of the transfercase to inspect it since I had read that there is a circuitboard inside that is known for causing the issue. I couldn't get to it without total disassembly and I could find a write up from anyone else that had done the job. So I measured the resistance of the wires I could access and everything came out good.

However upon putting it back together the planetary gears inside the motor must have slightly shifted because it would no longer engage neutral. so I took it back apart and reclocked the gears. put it back on and when I pushed the neutral button I could hear the motor engage but it didnt sound "normal" so I must have botched the motor up during taking it apart and putting it back together. Then it acted liek it was shifting to neutral but shifted into 4 low and lit up on the dash that it was in 4 low. And then the motor stopped working and it was stuck in 4 low. so I took the motor off and I could manually move the shaft to engage 4 low, neutral and all wheel. So I think its safe to say that the transfer case side of things is working correctly.

I then manually put it in all wheel and then took the motor back apart and clocked it to match and reinstalled it so I can atleast drive the Jeep. But I am going to need to get a motor at the least. Rather that will also fix the service 4wd system message or not I can not say but I am hoping so.

I also removed the FDCM from under the rear seat and took it apart and inspected the green board it it still looked like brand new, no messed up solder or burn marks or anything. so I reinstalled it.

Put jeep on jack stands all the way around and put it in gear and listen to each corner and have no wheel bearing noises. I also have no abs lights,brake lights,traction control lights on and speedo works correctly. so I am going to assume it is not wheel bearing/speed sensor related.

At this point without chucking out a ton of money to chrysler to hook a scanner up to it I am thinking the issue is either in the transfercase motor OR possibly corrupt firmware on the FDCM.

I reaaaaalllllly hate Chrysler engineers right now which is saying alot from a guy who has been a life long Mopar fan/owner. What happened to the good ole days of a carburetor, lever action 4 wheel drive and minimal wiring...the basics. now you need a specialty computer worth thousands of dollars from a stealership to tell you anything thats wrong with your vehicle.

In the meantime if anyone has any ideas please feel free to chime in. I just wanted to update the thread with what I have tried so far and where I am at as things currently stand.

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #5 of 26 Old 09-22-2017, 07:45 PM Thread Starter
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I have had the jeep on jackstands on all 4 corners and confirmed all tire's move smoothly. When engaged in gear all tire's will spring together. And I have also tested to resistance and continuity of the actuators in both front and rear differential aswell as the leads at the fdcm that run to the actuators. Everything checked out good.

At this point I know I need a transfer case motor partially because of a fault of my own and partially because I see that ends up being a fix for a lot of folks and I'm crossing my fingers that after replacement it will fix the problem. I'll know more in a week or so once one is delivered to me. Otherwise if that does not fix the problem I am thinking the culprit may likely be the fdcm . There isn't much else I haven't checked that I could think would be the problem. But who knows on these newer vehicles with miles of wiring and a gazillion sensors lol. They sure are trying to phase out the average Joe mechanic.

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #6 of 26 Old 09-22-2017, 07:46 PM Thread Starter
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Today the new T-case motor arrived. I disconnected the battery for about a half hour, Removed the old T case motor and installed the new one. Connected the harness. Reconnected the battery and immediatly the service 4wd system messaged popped up on the evic again. So the problem is still there. 4 low still will not engage. I can switch in and out of neutral.

I tried the fuse trick a couple times again and still just like before it does nothing for my issue.

The battery tested good as I mentioned before but just for the heck of it to rule it out I pulled the battery out of my ram and swapped it into the Jeep and hooked it up. Again the same service 4wd message immediately pops up.

Tomorrow a buddy of mine is going to let me hook his diablo trinity up to it and I am going to see if I can get it to pull any codes. If not, I am going to try and get it down to my brother in laws shop and have him hook his big dog scanner up to it and see if that brings anything up.

At this point I am either thinking that I fixed the problem and I need to clear a stored code from the system OR the problem is with the FDCM. OR....who knows at this point. I have about exhausted all ideas and ran all the tests I could check myself without throwing out the cash at chrysler dealer and having them hook their scanner up to it.

Please if anyone has an idea...by all means chime in!

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles

Last edited by motorhead86; 09-22-2017 at 08:10 PM.
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post #7 of 26 Old 09-22-2017, 09:52 PM
CavallinoRed
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you've probably been done this road already as sounds like it's be a long trip but there was a service TSB on '05 about vehicles displaying the service 4x4 system error but with no DTC in memory which sounds like what you have here.
http://www.wkjeeps.com/TSB/tsb_wk_2101406a.pdf

I would think that between N23/P73 this would have been covered but maybe not. Best i can think of as really sounds like a mystery since there are no codes. To confirm A dealer StarScan shows no DTCs at all?

Has the FCDM ever been replaced and/or are you sure it's the right one for your year? Later box might cause this.

I know you tried a battery swap but voltage sounds on the low side and they're very temperamental about that.

Not having and diagnostic error codes. That's the odd part.
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post #8 of 26 Old 09-23-2017, 05:40 AM
jeepstercanada
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Check for codes I had a bad lf weel bearing. Abs sensor part of unit, the 4wd needs see those speed senors. I changed it and all good now
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post #9 of 26 Old 09-23-2017, 06:43 AM Thread Starter
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Quote:
Originally Posted by CavallinoRed View Post
you've probably been done this road already as sounds like it's be a long trip but there was a service TSB on '05 about vehicles displaying the service 4x4 system error but with no DTC in memory which sounds like what you have here.
http://www.wkjeeps.com/TSB/tsb_wk_2101406a.pdf

I would think that between N23/P73 this would have been covered but maybe not. Best i can think of as really sounds like a mystery since there are no codes. To confirm A dealer StarScan shows no DTCs at all?

Has the FCDM ever been replaced and/or are you sure it's the right one for your year? Later box might cause this.

I know you tried a battery swap but voltage sounds on the low side and they're very temperamental about that.

Not having and diagnostic error codes. That's the odd part.
Yeah ,I have gone over all the TSB's. Both the N23 recall was performed aswell as the P73 recall which was the recall to fix the first recall haha.

NO I have not yet had it star scanned at the dealer!. I have been saving that as a last resort because I am sure the dealer will want upwards of $150 just to hook a scanner to it and tell me what the scanner says. So I am trying to exhaust everything I can think of that does not cost money troubleshooting first before I go that route. I tried the onboard diagnostics (3 turn key dance) and pulled no codes but as far as I am aware it doesn't report on codes related to abs/brakes/4x4 etc...etc... only basic engine codes...which would explain why no codes popped up. Today I am going to hook a friends diablo trinity up to it and see if it will pull any codes but I do not have high hopes. If that does not work I am going to take it to my brother in laws shop and hook his snapon VarusPro up to it and see if that picks up any codes. If STILL nothing THEN I am going to look into making a trip to a dealer for a star scan.

NO the FDCM has never been replaced and is the original unit.

As for battery ...I have tested it with both a toaster box aswell as volt meter. I also heard as you mentioned that these are temperamental if the correct voltage isnt on hand which is why I spent as much time as I did dinking around with the battery lol. With the volt meter hooked up and sitting in front of my windshield so I could see what was going on . Ignition off/engine off/doors closed I was sitting at about 12.6 volts. Ignition ON/engine off/doors closed I was getting about 12.4 volts. Ignition ON/doors closed/engine CRANKING I seen the voltage drop to as low as about 10.5 volts for a SPLIT second before returning to higher volts once running. Ignition ON/doors closed/Engine RUNNING I was getting 13.5-14Volts. Ignition ON/doors closed/engine RUNNING and giving it throttle of around 1500rpm the voltage would increase to around as high as 14.2-14.5 volts for a brief period before equalizing at around 13.5-14 volts once again. So the alternator appears to be doing its job and according to the toaster box and other folks who have had a battery issue on these jeeps...the voltages appear to fall into the acceptable range.

I also ran the same test on a family members 05 dodge caravan and got almost identical results. and ran the same test on my 11 ram 1500 4x4 5.7 and got almost identical results and for the heck of it took the battery out of my ram and swapped it and still got almost identical results when installed in the Jeep.

Plus the service 4wd system message pops up immediately as soon as the key is put into the ON position which tells me it is either a fault stored in the computer OR a currently failed part that is immediately reporting a failure. I would think that if it was voltage related causing the issue that it would trigger a message upon engine cranking when the voltage drops....which is not the case.

Thank you for the great suggestions though, I appreciate it and I am all for anyone tossing out ideas to bounce off me rather they are things I have already tried or not. So far though I have checked just about all I could multiple times over and it is all checking out good. Unfortunately its looking like it may come down to having to have it scanned to see if there are any "deep stored" codes related to the service 4wd system message.

I will not give up on the problem until I solve it though and I will be sure to keep this post updated so any other ( I am sure there will be others) that have this problem can have a better idea of what to do to their jeep . Thanks again and sorry for the long post, Just trying to make sure I get everything as accurately described as possible to eliminate any confusion.

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #10 of 26 Old 09-23-2017, 06:47 AM Thread Starter
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Quote:
Originally Posted by jeepstercanada View Post
Check for codes I had a bad lf weel bearing. Abs sensor part of unit, the 4wd needs see those speed senors. I changed it and all good now
I have thought a few times that it COULD be wheel bearing/speed sensor. However, I was under the impression that if it was one of those that I would not only be getting a "service 4wd system" message but that I would also be getting a ABS light/Brake light/Traction control light/ESP disabled message etc..etc.. When yours went bad, did you only have the service 4wd system message or did you have the other warning lights/messages?.

I had also doubted it being bearing related when having all 4 corners on jackstands and putting it in gear and listening to each wheel and hearing no bearing noise from any of them.

My next step will likely be trying to dig any codes out of it that I can so soon enough I should know if like you mentioned if there is a speed sensor code thrown. In the mean time if you could clarify your symptoms from when yours went bad it would be greatly appreciated. Thanks

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #11 of 26 Old 09-23-2017, 09:16 AM
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I had the message for months on mine, wasted some money throwing new differential actuators and a new T case shift motor with no dice. Had the dealer pull the codes and it said the t case clutches were shot! They said I needed a new case, but it was actually a replacement one from Mopar 20k miles old (orevious owner had it done under warranty, probably the same code....). I asked them to push the FDCM flash thru again, and they did and it has gotten rid of the codes and everything works great now. Its been about a month.


I would just pay the dealer the $150 or whatever and have them reflash it.

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post #12 of 26 Old 09-23-2017, 10:52 AM Thread Starter
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Quote:
Originally Posted by E-rok View Post
I had the message for months on mine, wasted some money throwing new differential actuators and a new T case shift motor with no dice. Had the dealer pull the codes and it said the t case clutches were shot! They said I needed a new case, but it was actually a replacement one from Mopar 20k miles old (orevious owner had it done under warranty, probably the same code....). I asked them to push the FDCM flash thru again, and they did and it has gotten rid of the codes and everything works great now. Its been about a month.


I would just pay the dealer the $150 or whatever and have them reflash it.
I agree that I don?t think it is worn t case clutch. I seen some other say that?s what they were told also and didn?t fix it. Since I can manually engage the selector shaft and all 4 wheel functions work correctly. I do think like you said that it could be module related.

Today tried a couple scanners and trinity tuner with no luck. Next step is my brother in laws snap on versus pro scanner and if no dice with that then the next step will be taking it to dealer to have it scanned.

In the meantime if anyone else has something to add. Feel free to drop a comment below. Thanks

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #13 of 26 Old 09-26-2017, 02:28 PM Thread Starter
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I went over the Jeep again the other night, Jacked it up and shook front end down AGAIN and listened for any wheel bearing noises....took the brake calipers and bridge and rotors off and tried using channel locks on just the hub flange to see if I could get any play and all of them had ZERO play. put just the rotors on and then wheel and spun the wheel and gave a good listen to them and absolutely whisper quite.

So I don't think the issue is wheel bearing related.

I unplugged the abs connectors in the wheel well and each one once unplugged would trigger a service electronic brake message on the dash aswell as ESP disabled and traction control light aswell as brake light. Plug the connectors back in and all is fine again aside from still having the service 4wd message.

So that leads me to believe that all of the wheel sensors are operational aswell.

I am beyond frustrated with this issue and would really like to figure it out before I am forced to take it to the dealer and pay for a scan.

Can anyone tell me, Will only a star scan from the dealer read a code from the service 4wd message?. Or will other scanners out there read what the code is?...if so, what ones?. So far it has been hooked up to advance auto's cheapo scanner, I have done the unboard diagnostics key dance, A friend of mines cheapo scanner and a friend of mines Diablo trinity chrysler tuner. everyone of them has shown ZERO codes.

And even after clearing the "codes" anyways with a scanner...the message remains. And even after unhooking the battery numerous times...the message still immediately displays. Which tells me this code is either stored somewhere that gets continuous power from something such as a built in cmos battery OR the fault is still present and immediately retriggers the service message.

Any and all help/ideas would be really appreciated here. I would like to get this taken care of as soon as possible. thanks

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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post #14 of 26 Old 09-26-2017, 10:04 PM
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Service 4WD System is probably the most frustrating issue with these vehicles.
This pops up after a code is stored. And will continue to display until after the code is cleared.
There are several scanners that can display and clear these particular codes. AUTEL® MaxiDAS® Automotive Diagnostic and Analysis System, 800.00 from HarborFreight.com. Bluedriver 100.00 from Bluedriver.com (needs a smartphone). Superchips 3870 and newer. As well as others.
The 2 recalls Jeep had for this were to reprogram the FDCM to drastically tighten the voltage parameters being read from the transfer case motor output.
I've got the same problem. But after I clear mine, it seems to stay cleared until I drive 75-90 mph on the freeway. That leads me to believe I might be seeing higher voltage during that time. Higher voltage in might mean higher voltage out of the tc motor.
As was mentioned by CavallinoRed these recalls caused this system to be very demanding of voltage control. I would make sure all the wiring connectors, ground cables, battery, etc in these circuits are 100%.
Mine had the first (N23) but not the second (P73) recall done. So I will be taking mine back to have that done. If that doesn't take care of it, I might start monitoring the voltage to and out of the tc motor to the FDCM.
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post #15 of 26 Old 09-27-2017, 11:02 AM Thread Starter
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Quote:
Originally Posted by beemer9 View Post
Service 4WD System is probably the most frustrating issue with these vehicles.
This pops up after a code is stored. And will continue to display until after the code is cleared.
There are several scanners that can display and clear these particular codes. AUTEL® MaxiDAS® Automotive Diagnostic and Analysis System, 800.00 from HarborFreight.com. Bluedriver 100.00 from Bluedriver.com (needs a smartphone). Superchips 3870 and newer. As well as others.
The 2 recalls Jeep had for this were to reprogram the FDCM to drastically tighten the voltage parameters being read from the transfer case motor output.
I've got the same problem. But after I clear mine, it seems to stay cleared until I drive 75-90 mph on the freeway. That leads me to believe I might be seeing higher voltage during that time. Higher voltage in might mean higher voltage out of the tc motor.
As was mentioned by CavallinoRed these recalls caused this system to be very demanding of voltage control. I would make sure all the wiring connectors, ground cables, battery, etc in these circuits are 100%.
Mine had the first (N23) but not the second (P73) recall done. So I will be taking mine back to have that done. If that doesn't take care of it, I might start monitoring the voltage to and out of the tc motor to the FDCM.
Thanks for the info. So the blue driver will read and clear these codes?. At $100 price point....thats cheaper than a trip to the dealer to have it scanned is....And I can read and clear codes whenever I want and WITHOUT being charged by a dealer each time!. If that is the case I may invest in a blue driver rather than throw my money away at the dealer!.

2005 Jeep Grand Cherokee Limited "WK". 5.7L HEMI , 4x4, 63,000 Miles
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