ABLS (Active Brake Limited Slip) uses the ABS system sensors to detect a slipping wheel and apply the brake(s) to that wheel to help send power to the opposite wheel. On a 4X4 Titan, we have this front and rear. And only in the rear when in 2WD.2007 TITAN LE said:While in 4X4 mode today in snow, when my drivers side rear tire slipped, it sounded like the antilock brakes kicked in only on that tire. Is that the ABLS working or is there a problem with my truck? It only made the noise while the wheel was slipping quite a bit, not when it had traction.