The wires have to be matched by function, not by color. Here is a link to the color code
for the stock radio harness in your Passport. Connect whatever color wire your Kenwood manual says is for 12V + (usually yellow for most aftermarket receivers) to the "red/white" in your Passport. Connect the Kenwood accessory wire (usually red) to the brown/white wire in your passport. Just continue matching up each wire function and colors on both ends.
Best would be an aftermarket wiring harness vehicle specific for the Honda Passport/Isuzu Rodeo. The Metra 70-7712 seems to be the correct one for your vehicle. Installer.com
probably has the largest selection of wiring harnesses available anywhere. They'll even match the vehicle harness to an aftermarket receiver harness and connect them using solder and heat-shrink insulation if you desire.
Most local car audio shops will carry some wiring harnesses. Also retailers like Best Buy may have them, albeit at much inflated prices. Online car audio retailers like www.crutchfield.com
have a good selection and their prices will probably be somewhere in between, lower than local but higher than Installer.com
Hope this helps.