Some people just don't know when to stop. Most people would call it a day after swimming a 1.5 km race. After that, they probably wouldn't race a mountain bike 30 km up a trail, then go for a brisk 11 km jog afterward. Yet, that's just what the XTERRA Global Tour off-road triathletes must endure just to finish, and that's the unstoppable spirit that Nissan sought to tap when it named its own off-roader "Xterra." Of course, everybody's got to stop sometime, unless perhaps, your ABS system is on the fritz.
Many manufacturers use separate computers to control the anti-lock brakes and the engine. The ABS computer is a simpler beast than its sophisticated engine-control counterpart; more of a simple-and-tough pickup truck than a European sports car. Modern ABS computers, like the one used on the Xterra, can network with the engine and chassis sensors and controls to offer traction- and stability-control functions. Those functions are controlled by the ABS control module. The Xterra ABS computer connects to a single warning light on the dash, which illuminates whenever there's a problem with any of its functions.
Nissan issued a technical service bulletin resulting from large numbers of owner complaints on malfunctioning wheel speed sensors on 2007-to-2013 models. The wheel speed sensors are the eyes and ears of the ABS computer; any malfunction with any one of them will trigger a light and make your system malfunction. Speed sensor failure is a common malfunction, so odds are good that this is your problem. However, a failure in the pressure modulator or the associated sensors and controls that make the system work will also trigger a light.
The ABS control module itself has a small LED light that you can get to flash in sequence, giving you a numerical fault code, like ancient ALDL "blinky light" computers. But the procedure for jumping the terminals is easy to mess up, and computer damage can result if you get it wrong. Standard OBD-II scanners won't read chassis codes from the ABS module, so you'll need to use a Nissan-specific scanner to do it. Dealerships will read your codes for a fee, but some Nissan-approved aftermarket scanners can pull these codes as well.
