How to Hardwire a Car Stereo

Remove the old stereo, if applicable. Prepare the opening by clearing debris and locating the adapter plug or wires. Most dashboards will unscrew or unbolt, allowing access to the radio harness and wiring. The opening may require an adapter plate, depending on the unit and vehicle, that fills the opening completely. The wires inside the opening should be stripped to a depth of 1 inch, unless a radio wiring harness adapter plug is in place. Most cars and trucks will have the adapter plug, and this can be directly connected to another adapter plug that will fit the radio unit.

Splice the wires of the new stereo to the adapter plug by matching the color of the wires and twisting them together after stripping the insulation, using the provided diagram. Most stereos are standardized to the common "white/gray/green/purple" style, which designates the speaker and power connections. Most times, the yellow or red wire is the primary power lead, and there will be a similarly colored wire for memory functions. The black wire is the negative power coupling, and should be connected to a solid ground on the vehicle's body. Wrap all connections with a liberal amount of electrical tape.

Connect the adapter plug to the car's stereo wiring harness by pressing the plastic plug into the socket until it is firmly seated. Some types will have an audible click when the plug is properly connected.

Test the stereo's functions, and the speaker output, by powering the radio and adjusting the output with the fader and balance controls to test each speaker individually. Any issues with speaker output should be corrected before mounting the stereo into the dashboard.

Mount the stereo into the dashboard by placing it into the adapter plate, and then reusing the bolts from the old radio to secure the stereo to the dash opening firmly. Replace any dash panels that were removed, and test the stereo again to ensure that the connections are solid and not crimped by pressing it into the dash.