Installing Or Replacing A Car Stereo
Receiver
(also known as a "head unit")
(General considerations applying to most installations)
MOST IMPORTANT!! Receivers can be very different! Read the instructions that came with
your unit. They will usually identify the wires and their connections, as well as contain
special instructions. This information may be on one of the unit covers as well. The unit
wiring colors will differ from the car's own wiring scheme.
TOOLS YOU WILL NEED: wire strippers, pliers, screwdrivers, wire crimpers and wire nuts,
12-volt light tester* or, preferably, a Volt-OhmMeter, and electrical tape. (*Newer cars
have extensive internal electronics that might be damaged if a light tester is used.)
BE VERY, VERY, CAREFUL! The slightest slip may short circuit connections in the underdash
area that is often densely packed with electrical devices. Such damage could be expensive.
1) Remove the old receiver. Notice that it has a ground wire, a 12-volt electrical power
wire, and four or eight speaker wires. It may also have Connections for line inputs and
outputs for other devices like a CD changer, and/or power amplifier. Consulting the
instructions of schematic, note carefully the identity of each wire on a small piece of
paper, which can then be taped to the appropriate wire. The main wires should easily
unplug from the back of the old stereo. Almost every receiver will have it's own peculiar
plug, necessitating the removal of the old plug, and the connection of all the wires to
the new plug on the back of the unit.
Do not connect the main power cable, until all other connections are made!
2) Connect the positive [+] wire from each speaker to the positive terminal or wire end,
on the back of the unit. If connecting wire to wire, be sure to strip each end of
insulation leaving about 3/8ths inch of exposed conductor on each end. Twist them
together, and then screw a wire nut over the connection making sure that no metal in the
wire is exposed. Tape over with electrical tape.
3) Connect the negative wire [-] from each speaker to the negative connection on the back
of the unit. Follow the procedure outlined above.
4) Connect the ground wire of the stereo to a screw or bolt near where the radio is
mounted in the dash. Make sure the wire is attached to metal frame part with a known good
electrical connection to the battery negative. Do not attach to plastic or fiberglass
parts.
5) With the ignition off completely, pull the 12-volt constant voltage wire from the
cigarette lighter. Use the VOM* or test light to be certain you are selecting the right
wire; the light will go on if you have tapped into the 12-volt constant.
6) Connect the constant voltage lead from the receiver to the 12-volt constant. Connecting
the constant lead ensures that the stereo's built-in clock and memory features always have
power.
7) Find the ignition source. Turn on the ignition and select the wire from under the dash.
(An auto-repair manual such as "Chilton's" can help you identify the appropriate
wire.)
8) Pierce the wire with the VOM or light tester* probe. The light will go on if you have
the correct wire. To assure the accuracy of your selection, turn on the headlights; the
tester should continue to shine with the same intensity.
9) Connect the "turn on lead" from the radio to the ignition source.
10) Look for more electrical leads coming from the receiver. These leads make power
available when the unit is on and can be used to operate a power antenna and/or amplifier.
If you don't have these items, cut off any exposed wire end part and wrap the leads with
black electrical tape so that they do not touch a metal surface and short out.
11) Connect the line in and line out RCA stereo cables to the appropriate devices,
Amplifier and CD player, usually.
12) The remaining plug is for the antenna. Connect it to the car's antenna line.
13) Find the metal brace that comes with some units. Mount the brace to the back of the
stereo and to a secure surface under the dashboard. Attach the faceplate to the dashboard.
Put the knobs, if any, on the appropriate shafts of the unit.
14) If there is only one wire coming from the speakers, the speakers are grounded at the
car chassis. In this case, you may need to install new speaker wiring, if your receiver
requires electrical isolation of each speaker. |