I have a 99 XLS with control trac and am beginning to wonder if the 4WD is working properly.
While waiting for the Mrs to come out of a store during a recent snow storm, I began to play (as boys will). The truck would easily begin to fishtail all over the place. However a nice steady application of gas and it would pull right away without spinning a tire. I had the kid get out and stand away to watch the tires while I rompted it and she said the tires turned together for a moment then the rears just took off. All this while in the auto mode. I've also noticed that the front end will slide and plow, in tight parking lot corners with or without power applied. My only other 4X4 experience is with my old '81 Dodge truck with manual hubs. It sure didn't behave any of these ways.
Is the 4X4 on these set up to only operate under a certain speed or do I have a problem?

 

It has to see rear wheel slip in auto mode and then it will engage. It seems to take approx. 3-4 seconds to do so.

 

I've had a similar experience. The day after I bought my '99 Sport it rained. At the stoplight I stomped on the throttle and for split second I could feel the back tires start to spin. The Control-Trac kicked and I pulled away from the light in very smooth manner. In the snow from a standing start I again stomped on the gas and I was able to pull away in a very neat and tidy manner with no fishtailing. It was only while I was doing donuts in a parking lots with 6 inches of snow that I questioned if the Control-Trac is working. The back end was swinging wildly and I was getting quite a bit of understeer.

I'm really curious if anyone can tell me the parameters in which the Control-Trac will operate. What is distribution of power between the back and front...50/50, 60/40, 95/5? I've heard that only 5% of the power is transfered to the front. Will the Control-Trac kick at any spoeed or just low speed i.e. to pull away from a standing start?

 

If I remember correctly, only about 20% to the front.

 

You say it has to detect slippage of the rear wheels ? I would think to do that it would have to compare the front axle speed to the rear axle speed. let's see, rear axle= 40 mph, front axle=2 mph. I'd call that slippage. Maybe I didn't stay on it long enough, it was a small lot. 3-4 seconds is a long time if you suddenly hit a bad spot on the road. Sounds like it's sort of but not quite 4WD.

 

You would be correct in your belief.

 

I reckon it's still better than conventional 2WD. I only had slight probs getting around this winter.(the afore mentioned plowing front end in parking lots) Just got to learn when to depend on auto 4WD and when to use 4WD High. Still love the truck, regardless.
Thanks for the feed back.