97x - Converting AWD to 4WD

Maverick6587

Well-Known Member
I swapped out my burned out transfer case with a junk yard case. I just left the "new" transfer case unplugged, so it will last longer. I tried to get a few transmission shops to rebuild the broken case. One said he wouldn't even touch it and the other wanted like $600 or so to rebuild it.

1. I've never rebuilt a transfer case before, but the NP226 (trailblazer transfer case) looks pretty easy to rebuild. The fact that the one guy said that he wouldn't touch it has me a little worried though. Does anyone know if the 226 is built much differently than the 126? I understand that the 126 is for AWD and the 226 is for 4WD. I just don't know how different that looks internally.

2. Does anyone have a good rebuild kit they've used before for the NP126 case? I burned through 2 junk yard transfer cases (I didn't have time to return either of them), plus the original (3 cases).... So, I think I may have enough cases for spare parts safety, lol.

It's finally getting warmer and I'd really like to at least start working on one of the those cases, before it gets too hot. I can't wait to complain that it's too hot outside! ☀😎


EDIT: The attached files will be continually changing as this project progresses. Feel free to add suggestions. I will update the file names when they are updated to the date that they were updated on.
 

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Mooseman

Moderator
For all that, I would either make into a permanent 2WD or convert it to a 4x4 with the NP226 and a real axle disconnect. The part time AWD is such a stupid system that I call the "slip-bang" system. Burned TC's. stripped intermediate shafts, higher fuel use because you're always spinning the diff, driveshaft and TC, which could be the reason for the burnouts. I actually had that planned for my 9-7x but circumstances have changed. The worse would be wiring it in since they never came in a 4x4.

The NP226 is pretty robust and I haven't heard of too many of them dying except for the usual encoder motors or if they were badly neglected.
 
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Maverick6587

Well-Known Member
how the hell did you go through three transfer cases already?
The 1st one was from not knowing that my tires had to be within any variance of tread depth. The second one already had almost 300,000 miles on it. The 3rd was about the same as the second. I drained the fluid while they were out, to get ALL of the old fluid it and filled them with auto trak 2 oil. Just bad luck and used np126's are pretty hard to find at junk yard in my area. Learning a lot though.

For all that, I would either make into a permanent 2WD or convert it to a 4x4 with the NP226 and a real axle disconnect. The part time AWD is such a stupid system that I call the "slip-bang" system. Burned TC's. stripped intermediate shafts, higher fuel use because you're always spinning the diff, driveshaft and TC, which could be the reason for the burnouts. I actually had that planned for my 9-7x but circumstances have changed. The worse would be wiring it in since they never came in a 4x4.

The NP226 is pretty robust and I haven't heard of too many of them dying except for the usual encoder motors or if they were badly neglected.
Umm... I was actually thinking of doing that on the drive home today. If I didn't have to worry about snow, I would definitely make it a 2wd. I assume I would need to reprogram the computer, wiring/connector change and then possibly driveshaft u-joint change.

I'm going to have to find an awkward place to put the 4x4 switch, to stay inline with Saab engineering. Putting it in place of a cupholder just seems right.

Are the differentials (mainly the front) the same on the AWD and 4x4's? I just greenlighted myself on this project! Lol
 

Mooseman

Moderator
Are the differentials (mainly the front) the same on the AWD and 4x4's?
Yep and the TC physical swap should be the same too. When you grab the TC from a TB/Envoy, grab as much as you can like the disconnect, switch, connectors, speed sensors and all the wiring. AFAIK, the TCCM controls most, if not all, aspects of the TC, including the A4WD, which we never suggest using anyway. The Saab's BCM might not like the 4x4 TCCM and may throw a code and light the service 4x4 light. At worse, you could tape it.

That cup holder next to the radio is useless anyway, even if it's not broken, and that spot will better serve for the 4x4 switch.
 
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Maverick6587

Well-Known Member
Yep and the TC physical swap should be the same too. When you grab the TC from a TB/Envoy, grab as much as you can like the disconnect, switch, connectors, speed sensors and all the wiring. AFAIK, the TCCM controls most, if not all, aspects of the TC, including the A4WD, which we never suggest using anyway. The Saab's BCM might not like the 4x4 TCCM and may throw a code and light the service 4x4 light. At worse, you could tape it.

That cup holder next to the radio is useless anyway, even if it's not broken, and that spot will better serve for the 4x4 switch.
Ha, yeah that cupholder is toast. Nice suggestion.

Well... I'm a little excited about this. Nothing is going to get done at work tomorrow for sure! :rotfl:

At the junk yard. The 126's are about $200 and the 226's are $45. I'm still going to rebuild it, unless I can find one with less than 100,000 miles on it.

I'm going to have to order today tech 2 here pretty quick. My goal is going to be replacing all of these components when I pull the body this summer. Easier to lift the transfer case than lower it from the bottom. Plus the wiring will be a cake walk without having to deal with the under body spacing.
 

Mooseman

Moderator
If you do this, could you document and take pics? A write up would be good for those in the same situation or wanting to ditch the slip-bang system.

I don't know if a Tech 2 would actually be of any use to you since the 9-7x BCM can't be programmed with TB software. Way too different.
 
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Maverick6587

Well-Known Member
Would I be able to delete the AWD portion, like you would delete the SAIS on the pcm?
 
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Maverick6587

Well-Known Member
Sorry yes, so many pictures will be taken. This will be one for my record books, lol. I'll do video as much as I can also. This one might have to go to YouTube.

I can't wait to learn how I could have saved a day or two in time after the fact.
 
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Maverick6587

Well-Known Member
I found this post (below) tonight, so that's a nice starting point. It's a fairly detailed walkthrough of removing the body from the frame. His is the v8 version, but most stress should be fairly similar.

I did forget about the ac lines though. I'll have to have that emptied before I start. Good thing Harbor Freight has an evacuator/vacuum pump and manifold gauge!

 

Mike534x

Well-Known Member
If you do this, could you document and take pics? A write up would be good for those in the same situation or wanting to ditch the slip-bang system.

I don't know if a Tech 2 would actually be of any use to you since the 9-7x BCM can't be programmed with TB software. Way too different.
Out of curiosity, what would the odds be of him using a BCM/PCM from a Bravada or Rainer? I'm kinda just throwing ideas out there, but considering the Saab is almost identical to those two, it should be a bit more friendly for this project?
 
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Maverick6587

Well-Known Member
Out of curiosity, what would the odds be of him using a BCM/PCM from a Bravada or Rainer? I'm kinda just throwing ideas out there, but considering the Saab is almost identical to those two, it should be a bit more friendly for this project?
Mooseman is more familiar than I but, I think those both carry the NP126 transfer case. I actually pulled one of my doner transfer cases from a Rainier and it was an NP126. Keep the ideas coming though! I'm all-in on this one.
 

Mike534x

Well-Known Member
Well I mean, if the BCM from a Bravada or Rainer was compatible. Then it could be flashed, and you could have a 4x4 system used in the Envoy or TB.
 
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Maverick6587

Well-Known Member
Ah, I think I understand what you're saying. I think we'll have to wait for Mooseman on this one. I know he said that the 97x BCM was too different to swap with a trailblazer/envoy but, I don't know if the same is true for the Rainier. The 97x is the upgraded version of the Rainier/Bravada, not sure which. Possible though I guess.
 

Mooseman

Moderator
I think no other BCM would be compatible because of the Saab's unique features like using the turn signals as DRL, HIDs (V8), having PassKey 3 rather than Passlock (yes it has a chip), DIC message for fogs and weird headlamp washer operation.

But then, the BCM might not care depending on how and what messages are sent between the TCCM to the BCM. If the TCCM, whether it's a AWD or 4x4, doesn't send a message saying to turn on the service AWD (or 4x4) system light, it might stay off. This is all hypothetical as I have no idea how they really interact. Hopefully the TCCM does work independently and will operate the encoder motor and the disco properly.
 
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Maverick6587

Well-Known Member
I changed the name of this thread.

I think if I pull the TCCM from the same vehicle I get the TC from, I think it'll work. I can't imagine that the BCM has any commands over the TCCM to stop it from doing it's just. I agree that the TCCM will probably send a code/error to the BCM possibly, but I don't think it will.
Worst case scenario here is that I pull everything and just convert to a 2WD vehicle.

Does anyone know if limequat has any knowledge of the TCCM or BCM communication/coding, or is limequat mainly a PCM programmer?
 

TequilaWarrior

Well-Known Member
Bravada AWD owner with ~250k miles here. Purely conjecture, but: It is more likely that the TCCM sends a "good/bad" signal to the BCM for AWD/4WD status than anything more complicated. However, I've heard of weirdness with swapping parts that talk on the car's communication bus refusing to talk to other components because the VIN doesn't match between components. Whether the TCCM does this, I don't know. Also, it being a Saab and an '06 - I'm not sure whether it has the simplistic traction sensing system my Bravada has which I believe works by borrowing the ABS sensor signals from the 2 fronts and comparing them to the output shaft speed sensor from the tranny (or something really close to that). Didn't they at "stabilitrak" at some point? I wouldn't be shocked to find that Saab's got it earlier than anyone else. That being said - if you're using the entire 4WD system (wiring, disco, tcase, etc...) you should be OK if the signal to the BCM is good/bad vs anything more complicated.
More conjecture (slightly off the AWD/4WD topic) - the Saab's BCM shouldn't be too wildly different. GMT360's destined for certain foreign markets had off the wall features that the BCM has to account for (rear fog lights is one I know of). HID and turns as DRL really isn't that crazy and Rainiers and TBSS's came with V8's and AWD. I believe they had different Tcases for V8 and Aero models - torsen type, I think.
 

Mooseman

Moderator
Here are the schematics for 4x4 and AWD systems. Although for the data link, it just shows for both that it's connected to the "network" but only shows the connection to the cluster for the light. I have a feeling that it's the BCM that commands that light because I once completely removed the TCCM and the light still came on. Like @TequilaWarrior mentioned, I also think it just sends an "I'm OK" signal to the BCM. At worse, if they don't play nice with each other, just leave the DLC from the TCCM disconnected and rip out the LED for that light. I think the 9-7x BCM can stay as-is.

And both also use the front and rear TC speed sensors for AWD engagement so there shouldn't be any ABS sensor issues. It's not like we use that stupid setting anyway.
 

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Maverick6587

Well-Known Member
I think I'm going to start a few Word docs to keep some ideas/plans active and easy to follow. I'll post them in my first post and keep uploading to replace the original as I update them.

Word docs that I plan on listing/keeping updated.
1. Ideas
2. The Build - Steps that need to be taken in order (or some kind of order) for this to be completed
3. Money - Cost associated with a parts and tools list
4. Pictures - not necessarily in a Word doc, but maybe
Edit: I'll add the date that they were updated to the doc file names.

Unless someone has a better idea to keep this more focused on the plan/process/steps to be taken to carry this project out?

I also want to thank everyone for all of their input and ideas! We're going to have to do a meetup after this one!
 

Mike534x

Well-Known Member
It may not hurt, but have you tried calling PCM of NC by chance? They seem to be pretty knowledgeable with the inner workings of the PCM in this platform, they may be able to tell you more. I only say this so if you were looking to get a quicker answer, you could write off whatever won't work and focus on the ones that could. :smile:
 

Mooseman

Moderator
I wouldn't post the docs to the forum. We would wind up with multiple ones that can be either incorrect or not updated. You could have a running thread (this one) and then a separate final write-up as an article.

Good idea on reaching out to @Kelly@PCMofNC . @limequat is more a PCM tuner and standalone running engine type but may also have some insight.
 
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Maverick6587

Well-Known Member
@Mooseman I was just going to keep deleting the three files and then add the updated version. So there would only be the 3 files attached to this thread at any given time. If you would prefer that I do a write-up at the end with the files attached there, I can do that though, or both, your call.
 

Mooseman

Moderator
I don't have any trouble myself with that. Now just get going!
 

limequat

Well-Known Member
Hmm, not much to add here, but looks like a cool project. I will say that even though the PCM has a switch for 4WD, you can use 4WD PCMs in 2WD trucks and vice versa ...even without programming. I've done exactly one standalone TCCM and it seemed to be easily isolated. I agree with others here that it should work with minimal interface issues. Easy for me to say, lol
 
I swapped my 9-7x to use the 226 t-case and it works great. I didn't have to do anything with the bcm, I used a t-case control module from a 226 truck, ran the extra wires needed for the front axle disconnect and the brake on the encoder motor and everything functions as you would expect. The only thing I didn't do "as factory" is there is one wire that runs from the t-case module to the pcm that tells the pcm you are in 4-lo and I just tied that through a 100k resistor to ign+ to make the t-case module happy. It seems to go into 4-lo and work ok but I didn't know if the pcm even monitors that wire on the saab "tune" and since I don't plan on going rock crawling I didn't feel like messing with it.

 

Mooseman

Moderator
Congrats. AFAIK, as of right now, you have the only 4x4 9-7x.

Did you do this before or after seeing it here?
 
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Maverick6587

Well-Known Member
@droptopgsx
QN6NnhbgfOpoI.gif

Thank you for posting here! That makes this project a lot less stressful.
 
I had done research on this forum as my main concern was if the tccm was going to flag the service 4wd light due to a vin mis-match but it doesn't seem to care/doesn't have any error codes but I was mainly tired of the encoder motors failing on the factory case and also I wanted the option of 2wd and 4lo for gas mileage and 'towing from ditch' type situations.

We used the truck all winter with the swapped 4wd and never had any issues with it in any of the modes. I 3d printed that mounting pod/thing, I may redesign it later to look a little more "fluid" but I wanted to avoid cutting anything on the dash and I can reach the switch easily enough in it's position next to the console.

If you have any questions LMK.
 

Mooseman

Moderator
And all of a sudden, there came a flurry of 4x4 converted 9-7x in the world. Well done!
 

ho3sticks

New Member
I have a pair of 97x Saabs and I love the cars and hate the awd system. I get snow in the winter and want to stop worrying about this silly system. My 5.3 car tcase is making funny sounds and I'm ready to make the swap before winter.

Did you make any list of the parts you gathered and the steps you took. I've reviewed your posts but I'm just getting into these systems and I'm not up to speed yet. I've identified a guy parting a 4x4 tb and I'd like to get as much off one vehicle as I can.

Thanks in advance for your assistance.
 

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