Classic/Antique Car Repair: 1966 Impala radio, auto literature, radio wiring

Question
I have a (new) Impala OK to me...  Radio wiring cut, I found old radio in trunk
but I don't know how to test it to see if it works and which wire is
power/speaker ground, there are just 3 in a row or tabs.  I am wondering if
you can help, I have 8 Ohm speaker as original too, I'd love to put it all back
and make it work if only AM, any suggestions would be of help.  I appreciate
it.

                                                                    Regards,
                                                                    Rod Kenny

Answer
I am not sure I understand your question completely, but if you are saying there are 3 wires there, total, the way to determine which is which requires that you know the color code, which is in your shop manual. If you are going to be keeping this car, and don't have the factory shop manual for the car, you will need to get one, because most shops are not going to have the information around anymore.

Contact one of the auto literature dealers (I use Ed Faxon at www.faxonautolit.com, but there are many others), they will have the shop manual for you.

If you want to try to dope it out without the manual, and if you have an ohmmeter and know how to work it, see if you can find which of the wires changes in resistance to the chassis of the radio when you turn the on-off switch (on the volume control) off and on.  If you can find one wire which goes from open circuit with the radio turned off to a low resistance (say a few ohms), with the radio turned on, that wire is the one that is supposed to go to the 12 volt radio fuse in the car.   If there are two wires that change when you turn the radio from off to on, the second wire is also supposed to go to 12 volts, but it is for the dial light, which when you install it in the car would be connected to the other dash lighting wires.   The other wires on the radio will be for the speaker.  With the radio out loose on the bench, you can connect them either way, the speaker doesn't care about polarity in this case.

If you want to check your speaker separately, take two wires and connect them to the two terminals on the speaker, and using a "D" cell flashlight battery, hold one of the wires on one end of the battery, then tap the other wire on the button on the other end of the battery. If the speaker is good, you will hear a "tick" out of the speaker.  If it is a really good speaker, you will hear a sort of "thump" and see the voice coil move in or out when you do this.  If speaker doesn't make noise or move like this, the speaker is bad.

To test the radio, you will have to hook up all the wires, ground the radio chassis to the negative terminal of the car's battery (or any good ground on the car) and plug in a car radio antenna to the jack in the back of the radio - just lay the antenna on some non-conductive surface - if you live near a big town, you should be able to pick up some local stations that way.

Dick