Head UnitsDo you hate the inexpensive looks of the factory CD player that is in the center of your dash, but like how the factory audio system functions and sounds? Good news, there are interfaces available that allow you to keep the factory OnStar and Bose systems, and give you the freedom to replace that tired-looking head unit without compromising the other components. Many of these systems allow the aftermarket head unit to maintain the use of factory operations, such as the OnStar integration devices that override the stereo and play through the front speakers while muting the new head unit. Also, these devices will not damage or interrupt the factory data bus systems in late-model vehicles that have warning chimes, audible turn signals, and other factory sounds.
Steering Wheel ControlsThere are interfaces for steering-wheel controls that allow you to upgrade your factory stereo to aftermarket and still keep those functioning as normal. These interfaces work on most vehicles and with most aftermarket receivers. If the steering-wheel control uses a dual-wire Controller Area Network (CAN) bus to control the factory radio, there is an add-on module that will interpret the data protocols from the steering wheel to a usable signal and send commands to the other interface. The module will not interrupt or disable the vehicle data bus.
You can also convert your steering wheel to a multiple-function control. These interfaces maintain normal control and operation of the factory stereo, but will allow you to control most other audio and video products that have an infrared remote (IR) control. This way, you don't have to worry about losing the DVD player remote, and you can control the video system without taking attention away from the road.
VideoYou essentially have a monitor when you upgrade to the factory navigation, but it will only display the navigation maps, preset stations, CD choices, and maybe the audio system setup. Why not add an interface to allow you use the screen as a video source? Designed as back-up camera interfaces-our guess is for legal purposes-these are externally wired and basically interrupt the video signals going from the GPS device to the display. The audio is then transmitted through an FM modulator, so you can do audio and video with the flip of a switch.