Driver’s seat position sensors are designed differently for the DRIVER SIDE Toyota seats. Their purpose is to magnetically track the position of the seat. Too far forward and the airbag is shut off. There is an early "U" shaped hall effect sensor found on most early airbag equipped Toyota vehicles. Later it was changed to the integrated magnet type and was easier to integrate into the rail design. 
 
The Tolerance Stack jumper harness uses all OE pins and connectors to convert from one style sensor to the other. In our case the reason for the development is when you are not using the original slide rails your vehicle came with, we don't usually have control on what the slide rail came with, sensor wise. This jumper cable guarantees you have the proper connector for the SRS system to function correctly. 
 
NOTE: this is not the same issue as the Driver’s Seat Position Sensor Extension Harness, that one is to lengthen the harness.