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Discussion Starter #1
As you might know, I have gone through 2 transfer cases in a matter of a few months. The only conclusion I can come to is when they updated the ECM to add the knock sensor, all the problems began with the AWD system. Fast forward to last week, they replaced the catalytic converter at 50% of what it would cost and I told them to reflash the ECM----they said it would be an additional $129. The car was done, no more CEL and they said they reflashed but did not charge me. When I got home I checked the work order and they did NOT flash the ECM. I called up and he put me on hold and said they would not and could not flash the ECM because I have the latest firmware. I tried several times but it was a no go.My concern is when they replace the transfer case, they said they'll replace again, but that's it. If it fails they will not replace a third time----I simply can't see it working this time. So I came across this and wanted to get your feelings on what to do---is it worth it doing myself? Is the dealer full of crap?

 

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As you might know, I have gone through 2 transfer cases in a matter of a few months. The only conclusion I can come to is when they updated the ECM to add the knock sensor, all the problems began with the AWD system. Fast forward to last week, they replaced the catalytic converter at 50% of what it would cost and I told them to reflash the ECM----they said it would be an additional $129. The car was done, no more CEL and they said they reflashed but did not charge me. When I got home I checked the work order and they did NOT flash the ECM. I called up and he put me on hold and said they would not and could not flash the ECM because I have the latest firmware. I tried several times but it was a no go.My concern is when they replace the transfer case, they said they'll replace again, but that's it. If it fails they will not replace a third time----I simply can't see it working this time. So I came across this and wanted to get your feelings on what to do---is it worth it doing myself? Is the dealer full of crap?

I think you have to have the GDS software along with the connection to even attempt this.

Your dealer is not totally full of crap. They can always reflash the ecu with the same firmware but if it gets damaged they are on the hook for replacement instead of Hyundai. So they would rather avoid unless there is a real need to it. Wonder if a hard reset is an alternative?

Out of curiosity, would it be worth visiting an independent shop to have the do a code scan and maybe inspection of the wiring to the case? Possibly it was damaged and is now shorting out?

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Discussion Starter #3
I think you have to have the GDS software along with the connection to even attempt this.

Out of curiosity, would it be worth visiting an independent shop to have the do a code scan and maybe inspection of the wiring to the case?

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Code scan? There is no CEL or code stored----check wiring?
 

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Code scan? There is no CEL or code stored----check wiring?
Ok misunderstood the original post but I would think if ECU programming is at fault, should see more things failing vs just the t case. So far just replaced that and cat, correct. No other things failed since then.

The awd failure...is it a lack of engagement of the rear axle? Intermittent engagement? Is the awd light coming on or blinking?

Diagnostic path would be to look at anything directly related to the awd system. ECU plays a part but not the main controller...that's the awd computer under the dash. Dealer or garage needs to scan that for codes or errors.

And I should have noted wiring is to the coupler assembly on the rear, not the t case

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is it worth it doing myself? Is the dealer full of crap?
I don't think the dealer is full of crap. It's not normally possible for a dealer to regress the PCM software to an earlier version. Older versions of the software are removed from the factory servers when a new version is made available. And if the earlier versions of the software aren't on the factory server that means you can't use a pass through programmer to regress the software yourself either.
 

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As you might know, I have gone through 2 transfer cases in a matter of a few months. The only conclusion I can come to is when they updated the ECM to add the knock sensor, all the problems began with the AWD system. Fast forward to last week, they replaced the catalytic converter at 50% of what it would cost and I told them to reflash the ECM----they said it would be an additional $129. The car was done, no more CEL and they said they reflashed but did not charge me. When I got home I checked the work order and they did NOT flash the ECM. I called up and he put me on hold and said they would not and could not flash the ECM because I have the latest firmware. I tried several times but it was a no go.My concern is when they replace the transfer case, they said they'll replace again, but that's it. If it fails they will not replace a third time----I simply can't see it working this time. So I came across this and wanted to get your feelings on what to do---is it worth it doing myself? Is the dealer full of crap?

To me it sounds like you have an honest dealer - and when you say they won't replace it a 3rd time - you are referring to new or used units ? I wouldn't put a used part in unless it is warranted - the shop doing the work needs to be proficient in determining that everything is in tolerance and the interface between the tranny output shaft and the transfer case is tight. If a shop won't warrant the part I'd find another shop who will.
Has anyone told you that the ECM could be responsible for transfer case failures ? I've never heard of such a thing.
 

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Discussion Starter #8
Nobody told me the ECM is responsible for the transfer case failure however after the update it exhibited the problem with the first transfer case. Literally after the knock sensor update my wife reversed out of the driveway and heard a squealing then a thump. We thought the e brake was stuck so I took it to the local mechanic. He confirmed all was good and the e brake worked normally and brakes look good as well. We noticed over the next few months the squealing and thump only happen in reverse. Then a short time later i tried to put out on a wet road and the front wheels spun and the anti slip light illuminated until i had traction. That's when we determined AWD was not working. Then we replaced with a used transfer case and right out of the gate it exhibited the exact same symptoms of the original then in a few months failed. It's either amazing coincidence or something in the programming that is causing it to stay in awd...I'm guessing.

If I hit the awd lock the shaft locks and does not spin freely. However if lock is not engaged the shaft spins freely unlike my 2015. There's no errors codes or CEL illuminated. I'm at a loss and the only thing I could think of is the ecm update. Is there anything else that could screw up the transfer case? Btw it has a 12 month warranty.
 

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Nobody told me the ECM is responsible for the transfer case failure however after the update it exhibited the problem with the first transfer case. Literally after the knock sensor update my wife reversed out of the driveway and heard a squealing then a thump. We thought the e brake was stuck so I took it to the local mechanic. He confirmed all was good and the e brake worked normally and brakes look good as well. We noticed over the next few months the squealing and thump only happen in reverse. Then a short time later i tried to put out on a wet road and the front wheels spun and the anti slip light illuminated until i had traction. That's when we determined AWD was not working. Then we replaced with a used transfer case and right out of the gate it exhibited the exact same symptoms of the original then in a few months failed. It's either amazing coincidence or something in the programming that is causing it to stay in awd...I'm guessing.

If I hit the awd lock the shaft locks and does not spin freely. However if lock is not engaged the shaft spins freely unlike my 2015. There's no errors codes or CEL illuminated. I'm at a loss and the only thing I could think of is the ecm update. Is there anything else that could screw up the transfer case? Btw it has a 12 month warranty.
Awd lock overrides the awd computer and energizes the coupler at the rear. Otherwise normal operation is handled by the awd computer based on inputs from the wheel sensors.

Think your awd computer is on the fritz or is not getting proper inputs.



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If I hit the awd lock the shaft locks and does not spin freely. However if lock is not engaged the shaft spins freely unlike my 2015. There's no errors codes or CEL illuminated. I'm at a loss and the only thing I could think of is the ecm update. Is there anything else that could screw up the transfer case? Btw it has a 12 month warranty.
I would be of the opinion that whoever is or has installed the transfer case should be verifying that the awd system is functioning as designed, this could be done while the vehicle is on a lift and placed into AWD drive lock - which means the transfer case would engage the rear wheels and they should spin freely, and also the vehicle taken for a drive with awd lock engaged. Not sure what you mean by spinning freely - there is some additional drag when the transfer case is engaged and the rear wheels should spin . Whether in AWD or AWD lock or not the drive shaft has to be spinning if your transfer case is functional. This of course with the engine running and in gear, all wheels off the ground.
 

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I would be of the opinion that whoever is or has installed the transfer case should be verifying that the awd system is functioning as designed, this could be done while the vehicle is on a lift and placed into AWD drive lock - which means the transfer case would engage the rear wheels and they should spin freely, and also the vehicle taken for a drive with awd lock engaged. Not sure what you mean by spinning freely - there is some additional drag when the transfer case is engaged and the rear wheels should spin . Whether in AWD or AWD lock or not the drive shaft has to be spinning if your transfer case is functional. This of course with the engine running and in gear, all wheels off the ground.
just to clear I should have said the rear transfer case/diff unit as the front transfer case is perpetually engaged - thus the driveshaft is always spinning.
 

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Yes, but the computer can and does still override the lock above a certain speed.
True but normal operation involves the computer varying the amount of power sent to the rear depending on the driving situation. This is done by controlling the oil pressure applied to the clutches inside the coupler as needed. As dtech noted, the driveshaft will always spin since it brings the power...no effect on engagement of the rear axle.

Unless I missed something from the OPs complaint, he has no awd outside of lock mode.

This would indicate that either the awd computer is failing or that something in the rear is not fully functional.

If only AWD lock is working then the computer is not processing correctly and failing to engage the rear as it should under normal driving or slippery conditions.

Either way a reflash of the ecm will not fix this. Nor will continuing to fire the parts cannon blindly. Diagnosis via a symptom chart and scantool is needed here before any more repairs are attempted.

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So IIRC he has replaced a rear clutch pack and 2 front transfer cases - with used parts. I don't think much detail was provided as to the proficiency of the shop used and what diagnosis had been done. Some shops will just replace any part the same they would as spark plus or an alternator, driveline components, especially AWD systems can have more inter-dependencies. So yes a good example of firing the parts cannon and used parts introduces another variable and I agree this isn't a bad ECU, but personally I have avoided the worthless 953 update so he has my empathy with respect to that "product improvement" being done to his auto.
 

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Discussion Starter #15
To be clear when awd worked on the original and second transfer case it worked automatically and when in lock. Now with the transfer case blown the shaft spins freely by hand unless the lock button is engaged. Meaning the rear differential is locking when set to lock and auto. My concern is how else could the transfer case blow if it simply is set to always be engaged.....meaning, it's simply always on.
 

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do you know the condition of the used transfer case or did the shop who installed it inspect the internals prior to installation ? In some cases used parts are tracked with respect to mileage of the donor vehicle, I think it's a fairly straightforward gear to gear type transfer case, but they can wear with the miles, especially if the fluid is never changed It's possible the used transfer case was on it's last leg. .
.
 

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The transfer case on these cars is completely mechanical. Not a single wire running to the thing. Nothing done to the ecm can affect it. The dealer cannot do software updates beyond what the gds will allow. If you have the latest update that’s all they can give you.
The symptoms you’re describing sound exactly like a rear differential failure. I have never seen a transfer case fail on a santafe, but the awd rear diffs fail all the time. It sounds like you got a misdiagnosis and replaced the wrong part. The transfer case is just an open differential, it will always send power the path of least resistance.
Everything you have described sounds like the transfer case is working perfectly and your rear differential is bad.
 

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but the awd rear diffs fail all the time. It sounds like you got a misdiagnosis and replaced the wrong part. The transfer case is just an open differential, it will always send power the path of least resistance.
The transfer case is not the same as an open differential, on these AWD Hyundai's it is a direct link and the driveshaft is constantly spinning - whether AWD is engaged or not. There have been reports of transfer case failures - but I think they may be tied to leaks or lack of maintenance. So what fails in the AWD rear - the differential unit itself or the clutch pack (which does control.power application to the the rear in AWD mode)

For this thread it may be advisable to read the entire thread - used parts were employed and that in itself can lead to issues.
 

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The transfer case is not the same as an open differential, on these AWD Hyundai's it is a direct link and the driveshaft is constantly spinning - whether AWD is engaged or not. There have been reports of transfer case failures - but I think they may be tied to leaks or lack of maintenance. So what fails in the AWD rear - the differential unit itself or the clutch pack (which does control.power application to the the rear in AWD mode)

For this thread it may be advisable to read the entire thread - used parts were employed and that in itself can lead to issues.
Sorry you’re right the transfer case is a power takeoff off the front diff. Power distribution is handled electronically via the abs and the rear differential. The rear diff is what contains the electronic coupler, not the transfer case.
When the rear diff goes bad the most common symptom is a thumping in the rear of the car when making tight turns. I don’t know the specific failure within the diff as it’s always replaced as a unit. It feels like it’s binding and releasing abruptly so something to do with the clutches in the diff itself.
 

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Discussion Starter #20
The transfer case is not the same as an open differential, on these AWD Hyundai's it is a direct link and the driveshaft is constantly spinning - whether AWD is engaged or not. There have been reports of transfer case failures - but I think they may be tied to leaks or lack of maintenance. So what fails in the AWD rear - the differential unit itself or the clutch pack (which does control.power application to the the rear in AWD mode)

For this thread it may be advisable to read the entire thread - used parts were employed and that in itself can lead to issues.
Thanks for your continued responses regarding this matter. Since the transfer case died (again) the rear is fine. Making tight turns at high and low speeds there is no noise or binding. Which has me wondering if the used transfer case was bad to begin with? If the rear differential we're trashed would it work correctly if the transfer case was disconnected? Or would there be binding in turns regardless? If it is the magnetic clutch, how can that be tested?
 
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