The software has been developed to keep the truck on the driver's intended path, much of which is determined by the steering-wheel angle. If, for example, the truck understeers (as most trucks do) into a corner and more steering angle is added because the truck continues going straight, StabiliTrak will apply the inside rear brake, which aids in making the truck turn the direction the steering wheel is pointed. As you'd expect from computer-driven electronics, this all happens many times every second, and the system is functional in any drive mode--accelerating, braking, or coasting. StabiliTrak has been programmed with some respect to how people tend to react in times of emergency or panic. However, we cannot emphasize enough that StabiliTrak is no substitute for common sense, good tires, or yours and anothers stupidity: GM trucks with StabiliTrak come with the same tires those without StabiliTrak have.
For this next-generation StabiliTrak, a new drive system has been developed. The viscous-coupled transfer case has been replaced by an open-differential, and no limited-slip differential is offered with StabiliTrak (optional on non-StabiliTrak equipped trucks). The open center-differential transfer case uses a 40/60-percent front/rear torque split close to the '02 model's 38/62 percent, and four-wheel-drive versions maintain the same low range near 2.7:1. In low range, the center differential is locked and some capabilities of StabiliTrak are disabled.
Despite our traction-hound-tester's best efforts, we couldn't make an '03 Yukon accelerate faster on an ice field with the system off than it did with the system on. By comparison, one of the competitor's trucks, with a system we're not fond of, was made to accelerate seven percent better on ice when the system was turned off. Another change to StabiliTrak includes the flexibility for more driver control. Current Escalades don't offer a method to disable the system, resulting in some performance tests being artificially limited. The '03 StabiliTrak system is defeatable to a point. All handling- and directional-control input is removed when it's switched off, but since the system is now responsible for traction control, it still provides brake intervention for front and rear wheels for traction-aiding purposes only. We proved this by pressing the magic button and shortly afterward executing an ever-so-graceful 270° spin.
Drivers will benefit from the StabiliTrak on '03 GM 1500-series trucks, even if they never know how often. And for those who prefer mechanical means for traction aid and their own steering input, GM offers that choice, too. Watch for a test in an upcoming issue.