AWD is really a two wheel drive temporarily? [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: AWD is really a two wheel drive temporarily?


Frayles
02-22-2008, 08:42 PM
Anyone had this happen to their AWD Rainier? The wife's 04 5.3 V-8 Rainier has been acting extremely strange. She came home in the midst of a sizeable snowstorm here in MA today and was complaining about how she was slipping and sliding all over the place. I attributed this to her heavy foot and told her to slow down. But the kid in me wanted to go and play in the snow so I decided to take her truck for a ride.
Well to my surprise and my wife's delight it was not her driving skills that are to be questioned. The AWD system will not engage and the truck just spins it's rear tires and I had to learn how to drive a rear wheel drive car in the snow again. HAHA There are no service 4wd lights or SES lights and I can't for the life of me figure out what is wrong. The truck has just shy of 36,000 miles on it. I know the system runs as a rear wheel drive until it detects wheel slippage and then engages the front wheels, but this cleary is not happening.
Anyone out there experinced this? I am going to have to take it to the dealer (thank God for GMPP) as the truck is long out of it's original warranty. Might as well get the front sway bar broken link fixed while it's at the shop. Any ideas on a potential fix for this? Other than this there have been no issues with the truck since I bought it new in December 2003

petevw
02-22-2008, 08:49 PM
Does the 4AWD light go on when you turn the switch?

I had a problem with mine that came & went....most of the time it was fine, but sometimes it wouldn't go on at all, and the 4wd wouldn't engage. Then, the next time I started the truck, it was back on.

Eventually, it stopped working altogether and the Service 4wd light came on, but before that, no light and no code......:weird:

Frayles
02-22-2008, 08:56 PM
The Rainier does not have a switch as it is full time AWD and I don't get to choose unlike the trailblazers and Envoys.

petevw
02-22-2008, 09:12 PM
OOOPS...I didn't know that.....sorry. :bonk:

So there's nothing (indicator light??) that confirms you're in AWD??

dsrtdukone
02-22-2008, 09:31 PM
I always thought that the Rainier with AWD had SmartTrak?????? If so, you should ALWAYS have power to ALL FOUR wheels.

LMMJ
02-22-2008, 10:09 PM
I always thought that the Rainier with AWD had SmartTrak?????? If so, you should ALWAYS have power to ALL FOUR wheels.

I believe the SmartTrak is like our A4WD and the lack of AWD may be due to high rear wheel speed when spinning to avoid the sudden "bang" engagement

Frayles
02-22-2008, 10:42 PM
I can always tell when the front wheels start to engage as you can feel the pull in the steering wheel. In the Rainier it takes minimal slippage of the rear wheels to get the fronts to engage. Hopefully it is not a major project and it's just something in the transfer case module that can be fixed via a scanner. I'll guess I'll just have to wait and see.

gearhead291
02-22-2008, 10:42 PM
well my bravada has smartrak and it has never done this
well here's an example of what it SHOULD do

http://www.youtube.com/watch?v=Smfp1rRwTrQ


sorry to hear about yours:cry:, hope the dealer can fix it:yes:

Ricky81
02-22-2008, 11:13 PM
its kinda funny, I checked into the manual for my Envoy in regards to how the awd/4wd works......Your rear tires will spin and with the awd on how it works if it senses any slipping of the rear tires it automatic engages your front tires for traction!!

Hey Frayles......I know you have the smartrack on the Bravada......I know on the Envoy and Trailblazers they have the button for traction control...if you do have this option....did you ever try it with that???? Underneath the shifter......:undecided

Frayles
02-22-2008, 11:24 PM
No, traction control and stabilitrak was not an option for the AWD 2004 Rainier. I know traction control was available on the 2WD models. I guess Buick figured that you would not need traction control if all the wheels worked in tandum.

dsrtdukone
02-22-2008, 11:31 PM
I can always tell when the front wheels start to engage as you can feel the pull in the steering wheel. In the Rainier it takes minimal slippage of the rear wheels to get the fronts to engage. Hopefully it is not a major project and it's just something in the transfer case module that can be fixed via a scanner. I'll guess I'll just have to wait and see.

If I understand what the guys are telling me at work: Your front wheels never disengage. They always have power. This power level varies depending on wheel spin, but the front's will never have less than 35% of the load.

Frayles
02-23-2008, 12:17 AM
Well then something is definitely wrong because the front wheels have always compensated when the back wheels start to slip. It has to be a computer (PCM) issue or the transfer case module in which it is not telling the front wheels to spin more when called upon.

2002SLT
02-23-2008, 11:00 AM
If I understand what the guys are telling me at work: Your front wheels never disengage. They always have power. This power level varies depending on wheel spin, but the front's will never have less than 35% of the load.

On the SS, yes. On the Rainier, no. They are completely different AWD systems.

Mr_Brooks
02-23-2008, 01:42 PM
No, traction control and stabilitrak was not an option for the AWD 2004 Rainier. I know traction control was available on the 2WD models. I guess Buick figured that you would not need traction control if all the wheels worked in tandum.

That is lame on GM's part.. My '06 has stabilitrak and traction control. Makes a noticeable difference on slick roads.

RayVoy
02-23-2008, 07:58 PM
The AWD trucks have a transfer case that is very similar to the case used by the 4x4 trucks. Of course, it doesn't have as many parts, but I believe it does have the encoder motor and the transfer case control module (not sure I understand why). I am sure I have read, on here, that this problem has been fixed by changing the encoder motor.
E-bay: http://cgi.ebay.ca/02-03-04-05-06-GMC-Envoy-Transfer-Case-Encoder-Motor_W0QQitemZ260212916973QQihZ016QQcategoryZ3373 1QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Frayles
02-27-2008, 10:32 PM
The dealer has had the truck for two days and they still can't figure out why the front wheels aren't engaging. They now have taken apart the transfer case, front differential and removed both front axles trying to figure out what part "failed". Stay tuned!

Frayles
02-28-2008, 03:25 PM
Just picked the truck up from the dealer and the reason for the AWD not working was:

"Found vehicle has a front differential problem. Found inner right front axle shaft bearing worn and caused shaft housing to walk when rotating which caused the intermediate shaft to strip the splines. Remove and replace right front differential shaft and bearing"

Additionally, I had them look at the front end because the truck did not feel anywhere near the way it did when it was new. Glad I did! They replaced all four sway bar links (front and rear) as well as the front sway bar bushings. The truck rides like a million dollars now.

The grand total......... $100.00 (deductible) Thank God for GM Protection plan.

ltdakheel
02-29-2008, 01:13 PM
i think to have switch to 4WD system is better than ful time 4WD becuase you can choose auto ant time and the system will act as AWD and after speed i think 60 or 50 mile will disengage the front wheel accept for traction if needed ( i want to say the AWD is not really all time 4 wd only at certien speed for fuel economy )

ScarabEpic22
02-29-2008, 04:34 PM
i think to have switch to 4WD system is better than ful time 4WD becuase you can choose auto ant time and the system will act as AWD and after speed i think 60 or 50 mile will disengage the front wheel accept for traction if needed ( i want to say the AWD is not really all time 4 wd only at certien speed for fuel economy )

Umm no, in A4WD the front axle is ALWAYS on, regardless of speed. The "AWD" system on our trucks (TB SS & 9-7X Aero excluded) are part time 4WD that just detects rear slippage and commands power forward. However I love A4WD and used it all the time (crappy Toyo Open Country A/Ts:mad::mad:) until I got new tires. Great for light snow conditions and if theres a lot of rain!:yes:

wbsterritt
05-29-2008, 01:35 PM
I am presently addressing this same issue on my 2003 Bravada with AWD (A4WD.) Haven't arrived at the root cause as of yet. Both the "I" shaft and the bearing assembly need to be replaced. I was able to salvage these two parts from a SELECTABLE 4WD(S4WD) Trailblazer. The "I" shaft is identical, however, the bearing assembly has the disconnect actuator (SELECTABLE) as part of the assembly- a horse of a different color! My intent is to wire up the actuator as a switchable unit thereby allowing me the option of 2wd or 4wd since everything else is identical physically and operationally. I will feel a lot more "warm and fuzzy" if I can figure out the root cause of the original failure. Will give you a follow-up.

wbsterritt
06-10-2008, 11:23 AM
Made the switch and everything went well. Only drawback is that the vehicle needs to be stopped before switching between 2WD and 4WD-not too inconvienent. On the plus side, my mileage went from an avg. of 18.7 to 19.8 mpg as of today. Currious to see if it changes more over time.

wbsterritt
06-16-2008, 09:48 AM
MPG up to 20.5 this weekend. Go baby!

chevytech04
06-16-2008, 03:29 PM
Ah yes....the storm in feb 22....i was at school when it started snowing at 12noon which is when school finished. I left school at 1pm then got home at 10pm. The traffic was horrible! :hissy: