Smartrac on a 99?

[Lou_Sand]

In making a hard turn from a dead stop, as from a parking place, my 99 chatters like brakes grabbing, PS relief valve sticking, tires trying to go sideways, etc. Seems as though we're in 4 wheel drive and CV joints are at their limit of angle. Is this normal for Smartrac? Just got this a little bit ago so I'm still learning its personality.

[Chris Stewart]

The '98's & up have that design problem. Seems the electro-magnetic clutch that applies power to the front differential...I think it's called an "encoder motor" will engage at inopportune moments as you've described and bind up the drivetrain.

When making a turn, the outside wheels rotate more times than inside wheels. If locked together, they'll bind...the inside wheels will try to turn as many rotations as the outside wheels.

If I was faced with this, I would install a simple switch to cut the electrical power to the encoder motor and turn it back on when the roads got snow or ice on them. No point in hurting parts.

[KidAce]

I experienced the same thing after I just bought my 2000 Bravada (a year ago), but it didn't menifest itself until I've driven for at least 15 minutes. This summer, I did the 60.000 miles Fluid change (Front & Rear Diffs first and then the Transfer case, 2 days later and then the Transmission, 2 days after that). The problem totally, I mean TOTALLY, went away after the Transfer Case fluid was replaced.

I'm not saying that will fix the problem, but it just might.

Good Luck,
Ace

[Lou_Sand]

Originally Posted by Chris Stewart

The '98's & up have that design problem. Seems the electro-magnetic clutch that applies power to the front differential...I think it's called an "encoder motor" will engage at inopportune moments as you've described and bind up the drivetrain.

When making a turn, the outside wheels rotate more times than inside wheels. If locked together, they'll bind...the inside wheels will try to turn as many rotations as the outside wheels.

If I was faced with this, I would install a simple switch to cut the electrical power to the encoder motor and turn it back on when the roads got snow or ice on them. No point in hurting parts.

Thank you!!! I'll let you know how I make out.
Lou

[Lou_Sand]

[quote=KidAce]I experienced the same thing after I just bought my 2000 Bravada (a year ago), but it didn't menifest itself until I've driven for at least 15 minutes. This summer, I did the 60.000 miles Fluid change (Front & Rear Diffs first and then the Transfer case, 2 days later and then the Transmission, 2 days after that). The problem totally, I mean TOTALLY, went away after the Transfer Case fluid was replaced.

I'm not saying that will fix the problem, but it just might.

Good Luck,
Ace[/QUOTE

Thanks! Due for fluid change anyway. I'll keep you posted.
Lou

[Lou_Sand]

Originally Posted by Lou_Sand

Thank you!!! I'll let you know how I make out.
Lou

Chris: I couldn't find any reference to an "encoder motor" in my owners manual, but there is a fuse for 'ATC' - 'automatic transfer case' in the underhood fuse/relay bank. So, I pulled the fuse and, as you suggested, my problem is gone. Now, if I can find appropriate wiring diagrams, perhaps I can cipher out the root cause of this difficulty. We had snow flurries yesterday,so I may need that AWD some day real soon.
Will let you know what my "final solution" might be.
Lou

[HVFD-Bob]

My 2000 Bravada is the first American car I have ever owned in 40 years and it will be the last. I have spent more money and time in repairs than any foreign I’ve had. One of the many problems was the Smartrak jumping. This was taken care of by changing to the so called “special” GM transmission fluid then driving for 50 to 100 miles and changing it again. The original fluid breaks down after 30,000 miles and does not allow the transmission to slip. All worked fine for six months then check AWD light came on and the truck would not go into 4WD. I was told the encoder motor failed and Olds wants $495.50 just for the part and $200 labor. I found a rebuilt one on the internet for $190 from National Automotive Lines in Shelbyville Indiana. The part should arrive in a few days should not be a big job to replace it myself. Anybody else had this problem or replaced the encoder motor?