The primary harness is the harness that plugs into your cars main entertainment system connector and converts it into a double ISO connector system (Universal). After selecting your primary harness you then select a secondary harness to connect between the ISO connectors and the aftermarket head unit that you have ( this is selected based on what brand and type of head unit you have. We carry both non steering wheel control type primary harnesses and steering wheel control type.

Toyota and Lexus cars ( after 2005) with OEM amplifiers to to a aftermarket car radio using phono line output from the radio.

Blue/ white is for cars with positive AMP turn on ( Most common)

White/ Black is for cars with negative AMP turn on

Black /white is and earth drain for the negative side of the Phono plugs (only needed if there is interference)