ABS LIGHT TURNS ON & OFF.

I am not sure that you got the correct info from this shop , because the Nissan ABS code format for this vehicle is code 36 for rear speed sensor and code 61 for pump motor fault. It depends on whether you have AWD as to whether you have more than 1 rear seed sensor. The most common sensor configuration in the rear is, it is mounted to the center of the rear differential. If so, it may be covered with metallic particles from the diff gears wearing. Try pulling it out and cleaning it. Does your Speedometer work ok?