Awd conversion

Amarks86

Member
I have an 05 Buick Rainier that the awd isn't working. Long story but shortly after I got it, the vehicle completely died. The dealership ended up replacing most of the electronics and said it was hit with a massive surge, possibly lightning. I realize awd is always active but the first time it threw power to the front wheels they locked in and it became terrible to drive (crow hopping, etc). I pulled the encoder motor and replaced it but that didn't fix it. Currently no encoder motor on it and I manually put it into 2wd. My question is: can I convert it to a manually engaged awd/4wd without changing the transfer case? A friend suggested figuring out the pinout on the encoder motor and bypassing the vehicle CPU so I can manually power it to move forward or backwards, I was thinking doing something mechanical like putting a lever on the spindle up through the floor board. Any insight would be appreciated
 

Mooseman

Moderator
A conversion to a real 4x4 system has been done before (check the faq). I suppose what you are asking is possible however the AWD transfer case lacks a brake on the clutch to hold it in locked front wheels. When the front wheels are engaged by the encoder motor, it slowly goes back to unlocked.
 
OP
OP
A

Amarks86

Member
A conversion to a real 4x4 system has been done before (check the faq). I suppose what you are asking is possible however the AWD transfer case lacks a brake on the clutch to hold it in locked front wheels. When the front wheels are engaged by the encoder motor, it slowly goes back to unlocked.
So if I use a pair of channellocks on that spindle sticking out of the transfer case to activate the front wheels it will eventually go back to 2wd?
 

TequilaWarrior

Well-Known Member
Why don't we try and straighten out what you already have?
When fully functional, the awd system in these is pretty darn good.
There are a handful of reasons your Tcase can be "stuck" in awd. A common reason - and an easy one to fix - is lack of fluid maintenance.
If your TCase has more than 50,000 miles on it without a fluid change it can easily be bound up. The cure, cheap at that, is to do 2 fluid changes separated by some driving - I did about 500 miles, I think.
Use only Auto-Trak II, GM exclusive fluid. It should be around $10 or so a LITER. It's sold in LITERS, not quarts. While the quantity difference is minimal, the capacity is stated in Liters. Regardless, change the fluid, drive 500 miles, change the fluid again. This will unbind the clutches in the tcase and allow any particles to be flushed out. This may cure your constant AWD problem. If it doesn't we quickly get into encoder motor and electronics diagnostics. For $40 worth of fluid, I'd flush the tcase before trying to Macgyver something.

Some things to keep in mind: the awd in these engages based on perceived wheel slip which is determined by comparing ABS sensors - so those have to be good. Also, you won't achieve torque converter lockup if the truck knows the AWD is stuck, thereby shooting your gas mileage in the butt a little bit. Your tires also must be very close in size to each other. 4WD and AWD systems in this platform are not very forgiving on mismatched tires - mismatched tires may cause binding in the tcase.
 
Last edited:
OP
OP
A

Amarks86

Member
Why don't we try and straighten out what you already have?
When fully functional, the awd system in these is pretty darn good.
There are a handful of reasons your Tcase can be "stuck" in awd. A common reason - and an easy one to fix - is lack of fluid maintenance.
If your TCase has more than 50,000 miles on it without a fluid change it can easily be bound up. The cure, cheap at that, is to do 2 fluid changes separated by some driving - I did about 500 miles, I think.
Use only Auto-Trak II, GM exclusive fluid. It should be around $10 or so a LITER. It's sold in LITERS, not quarts. While the quantity difference is minimal, the capacity is stated in Liters. Regardless, change the fluid, drive 500 miles, change the fluid again. This will unbind the clutches in the tcase and allow any particles to be flushed out. This may cure your constant AWD problem. If it doesn't we quickly get into encoder motor and electronics diagnostics. For $40 worth of fluid, I'd flush the tcase before trying to Macgyver something.

Some things to keep in mind: the awd in these engages based on perceived wheel slip which is determined by comparing ABS sensors - so those have to be good. Also, you won't achieve torque converter lockup if the truck knows the AWD is stuck, thereby shooting your gas mileage in the butt a little bit. Your tires also must be very close in size to each other. 4WD and AWD systems in this platform are not very forgiving on mismatched tires - mismatched tires may cause binding in the tcase.
Should I put the encoder motor back on before flushing the system or leave it off? I took it off because I was worried about breaking something
 

Mooseman

Moderator
All else being equal, I would put it back on to get the clutches working. If it's continuously engaging the front wheels, I would highly suspect a difference in wheel sizes front to back. One member had this issue and he had a set of new and worn tires causing it.
 

TequilaWarrior

Well-Known Member
All else being equal, I would put it back on to get the clutches working. If it's continuously engaging the front wheels, I would highly suspect a difference in wheel sizes front to back. One member had this issue and he had a set of new and worn tires causing it.
Precisely...
 

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