Rear speaker wire colors

[tompiantanida]

I am replacing the defunct AM radio in my 1966 with an aftermarket AM/FM radio. My town coupe has a rear speaker that I need to hook up to the aftermarket radio, but I can't find a wiring diagram for an AM radio with a rear speaker - not even in the manual - so I do not know what colors the wires are for the rear speaker. I can't just hook up to the original 3F/1M plug because two of the F plugs fed the internal fader for my original radio. Thus, I need to circumvent that plug and run wires directly to the front and rear speakers. I have identified the front speaker wire colors, but not the rear speaker wire colors. Help.

[cacockrum]

The wires to the rear speaker in my ’66 are black and black with a green stripe. They are routed within the main harness that runs under the center console, and exit the harness behind the rear seat. I could not find the rear speaker in the schematic portion of the Osborn electrical assembly manual, but the page that shows the mechanical assembly of the rear speaker shows the connector to be black with 2 conductors.

[tompiantanida]

Thanks for the information. Tomorrow morning, I plan to hook my ohmmeter up to the 3M/1F plug that the 3F/1M radio line connects to to determine whether there is any pair that shows the right resistance to be a direct connection to the rear speaker. I've already found the M/F plug to the front speaker, so I will use that to check the resistance. I realize that the ohmage of the speakers is impedance, rather than resistance, but the resistance should be about 3/4 of the impedance value.

[RedBird64]

I think I used some lamp cord to wire the rear speaker when I added it.
Is that bad?









JK!

[tompiantanida]

That should really brighten the sound.

I've been using my ammeter to test which leads go to the rear speaker. My AM radio has a four-lead connector, which means that my radio has a built-in fader. The fader on a '66 Thunderbird is pretty weird, in that it hooks the front and rear speakers in series and changes the balance with a rheostat. The wires to the front speaker return from the fader via a two-pronged plug. Since the front and rear speakers are in series, two of the connectors on the four-lead connector should read about 14-16 ohms when the front speaker is connected, and infinity when the front speaker is disconnected at the two-prong plug. I found these. Also, with the front speaker disconnected, there should be two connectors in the four-lead connector that reads 6-8 ohms, which would be the wires to the rear speaker. I found these. The trick then is to wire the front speaker at the two-prong connector and the rear speaker at the two connectors previously identified in the four-lead connector. I am preparing to do that and will tell you the results. One thing for certain: the fader system on a 1966 Thunderbird AM radio is weird. Incidentally, I also have a 1965 AM radio to play with. It has a four-lead connector, but its fader is wired differently from the 1966 model.

[tompiantanida]

OK, I've installed the radio. The connections to the front and rear speakers worked just the way I had hoped after identifying what I believed to be the speaker positive and ground wires. If anyone needs to make this hookup, let me know and I will send you a diagram.