Oldsmobile had been out of the truck game for some seven decades when the S-10 Blazer-based Bravada debuted in 1991, and its return to the industry seemed like good sense at the time. The Bravada differed from its Chevy and GMC siblings because, being more street oriented, it came with an all-wheel-drive transfer case that sent 35 percent of the power to the front wheels by default. At the end of the second generation in 2001, it still came with AWD -- but this version was a bit different.
The original Borg-Warner 4472 transfer case always sent at least 35 percent of the power to the front wheels, with more power sent to the front as necessary to combat wheelspin. This made the original transfer case the heart of a true "full-time" AWD system. By the time the second generation debuted in 1996, GM had realized that a constant power split was neither necessary in terms of performance, nor desirable in terms of driving characteristics. The New Process 136 transfer case used in this chassis defaulted to the rear alone, and sent power to the front only when the rear tires spun. This "on demand" AWD setup made the second-generation Bravada rear-wheel-drive whenever the computer wasn't sending power to the shift motor that engaged the front axle.
For this reason, yes -- unplugging the relay that sends power to the shift motor on the transfer case will completely disable the front axle. You can accomplish the same goal by unplugging the wiring harness plug from the shift motor on the transfer case itself. Just make sure you're unplugging the right one; there's a second plug and shift motor that engages the low range on the transfer case. If you unplug both of them, the transfer case will default to high range and rear drive, which isn't entirely a a bad thing if you never take your Oldsmobile off-road.
