At (1), connect the stereo supplied power cable with the installation kit supplied adaptor cable.

At (2), strip the end of the steering wheel interface cable and crimp on the appropriate "key" cable from the universal interface.

At (3), disconnect the appropriate patch cables and prevent them from shorting.

At (4), connect both leads to the steering wheel input control box.

The harness you made (and the antenna adapter) can be connected to your aftermarket head unit and the Suzuki cable interface.