Review on Upgrade Your Mazda Experience with the PAC RP4-MZ11 All-in-One Radio Replacement & Steering Wheel Control Interface by John Lewis

The first unit I received was a defective component. Unfortunately, due to the sheer amount of wiring and the complexity of these systems, I spent a few hours calling the wiring to confirm before requesting a replacement. I deduct 1 star for that. I will say I called PAC over the weekend (during business hours they should only support dealers/installers) and they tried to help troubleshoot even though I'm not a professional installer. I appreciated it. However, when I explained that my PAC harness already had RCA outputs, it confused the techs. He said his records showed that this should not have happened. It eventually worked, but it didn't inspire confidence that their tech support didn't seem to know what I had. I'm deducting another star due to the complex programming of the module and the fact that you can't toggle the display (miles to empty, average mpg, current mpg, etc.) on a Mazda CX-9 after installation. It's pretty close to ideal, but I wish it were easier to assign functions to buttons and easier to check that those functions work. Also, if you disconnect the car battery, the factory clock will be reset and you will then have to figure out how to reprogram it.