Removing the radio in a Honda Civic is not as simple as it is in some other models. The Honda Civic's electrical system is very sensitive, and the radio itself has a system programmed into it to deter theft. All of these factors need to be taken into account when removing the radio from the car.
Disconnecting the battery at the negative cable is vital any time you work on the radio or anything else electrical. You need to have the anti-theft code for the radio before disconnecting the battery. Input this code when installing the radio and/or reconnecting the battery, or else the radio won't work. Check your owner's manual for how to access the anti-theft code. You will need this code any time you disconnect and then reconnect the battery.
Disconnect the black cable by loosening the cable clamp nut and unsnapping the cable from the terminal. Be sure to set the cable someplace where it can't snap back onto the terminal by mistake. Wait at least three minutes after disconnecting the cable to ensure there is no power to the radio.
Once you disconnect and reconnect the battery, perform the idle learn procedure for the Powertrain Control Module. First make sue all the car's electrical components like the radio, lights and air conditioner are turned off. Turn on the engine, keep the car in "Park" or "Neutral," and bring it up to 3,000 rpm. Hold the engine at 3,000 until the radiator fan starts up or the engine coolant heats up to 194 degrees F, then let the engine idle for at least five minutes. Listen for the radiator fan to come on while the engine idles; any time the fan runs doesn't count toward the five minutes needed.
Remove the center trim panel from the dashboard; pry out the lower cover in the center with a trim stick or other flat tool, remove the mounting bolts at the bottom of the instrument panel behind the lower cover and pry the panel out with the trim stick. Once the trim panel is removed, reach back and unplug both the electrical wiring harness and the antenna from the radio. Now remove the mounting bolts--there are two on each side--so you can pull the radio out of its mounting bracket.
