Help! Wiring a '79 AM/FM to a power booster/equalizer??

[FORDification]

I had a good inexpensive Pyramid stereo setup that I was going to install into my truck. It included an AM/FM/cassette, a graphic equalizer/booster and four speakers. I got everything hooked up in my truck, but it appears that the cassette deck is dead. Since I need some tunes now, I decided I'd see if I could install the '79 AM/FM stereo radio and hook it up to the booster instead. (The equalizer has a CD input jack, so I can also use an I-pod in the future.) However, I'm not exactly sure how to do this wiring job, and could really use some help.

In a nutshell, I want to hook up this 2-channel Ford AM/FM radio which uses a common ground to my 4-channel booster.

OK, here are a couple pictures of what I've got, along with a factory '79 wiring schematic for the AM/FM stereo radio (click thumbnails to enlarge):



As you can see, there are two clusters of wires coming off this radio. There's a three-wire plug which I'm assuming is for the speakers, and the two-wire plug. Let's tackle the two-wire plug first.

There's a yellow wire w/black tracer coming into the green connector. I'm assuming that this is the 12V power source, correct? This wire turns into a black wire which then goes into a bundle of something. What is that bundle? I didn't want to unwrap it if unnecessary. So does this radio use a chassis ground instead of a standard black ground wire? The blue/red wire is for the dial illumination light.

OK, now the speaker connections. I've got my truck set up with four speakers, two in front and two in back, each with a positive and negative connection. However, this radio is only set up for two speakers (white/green and orange/green) with a common ground. I want to hook this up to my booster/equalizer. I'm including the wiring schematic for the booster:



What's confusing me (and trust me, it ain't hard to do!) is that it appears in the above booster schematic that the speakers are grounded to the chassis, yet the warnings specifically state NOT to do that. As shown in this schematic, the booster has green & green/white input for the left channel, and gray & gray/white input for the right channel...but I'm not sure which is the left and right channels on the Ford radio.

So...how do I hook up this Ford AM/FM with a common ground to this booster without damaging anything?

[mr_josh]

Thaaat's not too hard. Let's look at what you've got:

On the Ford schematic that you posted, you've got two speakers using a common ground. From the radio you've got a Purple wire labeled "784" on the schematic. This is the "-" side of each speaker. Then you've got an orange wire coming out of the radio, that's the Left side speaker "+" and a white wire that is Right side speaker "+".

On the other radio harness, you just have two wires, blue with red stripe is obviously illumination, you figured that out, and yes, probably it is grounded either through the chassis or the shield on the antenna cable.

To run it through your equalizer... that's a little tricky because I don't know that I trust their diagram. They show the solid colors as being the "+" inputs, but they show the solid colors as being the "-" outputs.

I would think... and this is just a guess, that you would connect the Green and Grey wires on the input side of the equalizer to the Purple wire on the back of your radio. Then connect the Green/White on the equalizer to your radio's Orange wire and the equalizer's Gray/White wire to your radio's White wire. Then connect your speakers to the equalizer as shown for a four speaker configuration. Do NOT ground the "-" side (Purple wire) of the input to the equalizer, that wire should be grounded internally.

After that, just plug in an antenna to make sure you have a ground (and maybe run an alligator clip from a good grounding point to the radio chassis), put 12v+ to the wire on the radio, ground and power to the equalizer, and let 'er rip!

I think!

[fordman]

out of the speaker wire plug is a red white and a black. the black is probably ground. the other two are power to the speakers for each side. if you hook up each side to the wrong side the radio will just work backwards. the black would just need to be split off and go to all speakers. i think when hooking up amps and stuff liek that. the speaker wires go to the amp . and then the amp goes out to the speakers. if the amp has a ground then the radio ground would go to the amp. and then onto the speakers. if it doesnt have a ground then the radio ground will go to the speakers. if you get the sides mixed up and the radio works backwards just swap the sires from side to side. at the radio connection.

[FORDification]

Thanks guys...I appreciate the input. There are a lotta things I'm good at, but trying to understand some aspects of electrical wiring makes my head hurt.

So using mr_josh's advice, I whipped up this little diagram. The factory wiring diagram shows a purple wire as the common ground, but my radio uses a black wire. This homemade diagram is labeled as such. This is what you're suggesting, correct?



Just wanted to verify before I started hooking things up.

[fordman]

that looks right to me.

[Thunderfoot]

See notes below and I have also attached a colored diagram to help...

There's a yellow wire w/black tracer coming into the green connector. I'm assuming that this is the 12V power source, correct? This wire turns into a black wire which then goes into a bundle of something. What is that bundle? I didn't want to unwrap it if unnecessary. Inside this bundle is a "choke" it is an electrical device to filter out noise on the power coming into the radio So does this radio use a chassis ground instead of a standard black ground wire? Yes, they are usually grounded through the mounting stud on the back of the radio The blue/red wire is for the dial illumination light. Correct

What's confusing me (and trust me, it ain't hard to do!) is that it appears in the above booster schematic that the speakers are grounded to the chassis, yet the warnings specifically state NOT to do that. As shown in this schematic, the booster has green & green/white input for the left channel, and gray & gray/white input for the right channel...but I'm not sure which is the left and right channels on the Ford radio. For which colors are which channels (R/L) look at the connectors (C-) on the Ford diagram... You see C-507, C-508, and C-510 ??? look at the box to the lift and it describes where these connectors are on the truck. So for example C-510 is the connector on the "L.H. Door, low" this is the wire plug for the Left Hand speaker inside the door, which correlates to the Orange wire.

Thaaat's not too hard. Let's look at what you've got:

On the Ford schematic that you posted, you've got two speakers using a common ground. From the radio you've got a Purple wire labeled "784" on the schematic. This is the "-" side of each speaker. Then you've got an orange wire coming out of the radio, that's the Left side speaker "+" and a white wire that is Right side speaker "+". This is correct and colors are correct for right and left

On the other radio harness, you just have two wires, blue with red stripe is obviously illumination, you figured that out, and yes, probably it is grounded either through the chassis or the shield on the antenna cable. These radios are usually grounded through the mounting stud on the back of the radio, make sure you have a good ground connection there. Also from the factory ford diagram they do not show the speaker ground wire being connected to the chassis ground, so don't connect it to the chassis ground (it is just a common ground wire for the speakers)

To run it through your equalizer... that's a little tricky because I don't know that I trust their diagram. They show the solid colors as being the "+" inputs, but they show the solid colors as being the "-" outputs. I wouldn't second guess "their" factory diagram!!! Use the colors as they are listed in the diagram, they are listed the same way for both radio types so it does not look to be an error...

I would think... and this is just a guess, that you would connect the Green and Grey wires on the input side of the equalizer to the Purple wire on the back of your radio. Then connect the Green/White on the equalizer to your radio's Orange wire and the equalizer's Gray/White wire to your radio's White wire. Don't second guess the factory diagram... unless you have concrete proof to back up it is wrong or in error... Then connect your speakers to the equalizer as shown for a four speaker configuration. Do NOT ground the "-" side (Purple wire) of the input to the equalizer, that wire should be grounded internally.

After that, just plug in an antenna to make sure you have a ground (and maybe run an alligator clip from a good grounding point to the radio chassis), put 12v+ to the wire on the radio, ground and power to the equalizer, and let 'er rip! See note above on ground connection.

I think!

[FORDification]

Thanks to everyone! Got it hooked up today, and it works and sounds great! Think I'm gonna move the booster/equalizer to the glovebox though, just to keep the interior looking semi-stock.

[Thunderfoot]

Glad you got it working. The booster / equalizer will generate some heat, so not sure I would put it in the glove box... they need some air flow around them to keep them cool.

[FORDification]

Well actually I was planning on putting it behind the glovebox door, but removing the glovebox liner...building a bracket that would simply mount it behind the door, for aesthetic purposes. Since I'm getting ready to install buckets and a center console, I really don't need the glovebox, and it's the most convenient place to hide it but still have easy access. I'm thinking it'll still get adequate airflow if the glovebox liner is removed.

[Thunderfoot]

Yes that should be ok, just didn't want to see you put it inside the glove box liner where it would be like in a box, removing the liner so that it has open space to under the dash area should be fine.