So during my electrical escapades under the dash of the Dart, I'm also moving the Sony receiver up into the dash to replace the factory radio. The wiring will be really simple, save for one question. The Sony has a "dimmer" lead for attatching to the dash dimmer circuit.

What I can't figure out is which lead on the headlamp control knob is for the dimmer/dash lighting! That's a burly plug and the wiring diagram didn't help much

I want to wire that out to a small distribution box that I can easily connect the receiver's and the aftermarket gauges' dimmer leads to for a clean wiring job.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

What I did for my aftermarket gauges was to feed the light from the fuse box, I believe I put it on the headlamp fuse, I can't be positive. I will check next time I am at my car if you want me to. Lots easier then reaching all the way up to the dash. If memory serves me right I didn't need to tap into any wires the extra spade terminals were already availible on the fuse box.

That's what I had originally wanted to do, but as anal as I am about keeping things consistent, I wanted to have the lights on the dimmer circuit

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

That fuse is on the dimmer circuit.. ahh wait maybe it wasn't the headlight fuse there is a fuse in the block that goes to the dashlights... that one is deffinately tied into the dimmer function. My add-on gauge light deffinately varies brightness along with the dash lights when you turn the headlight switch knob.

Ah okay. Running that to a dist. block would be the best bet then. Sweeeet...

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Jopapa, If you are using a fused distribution block, be sure that you don't fuse the ground (negative) wire. Although it is unlickely that the head unit would blow a fuse, should something short or malfunction causing a fused ground to blow, it will look for a ground somewhere else. That can cause a serious problem The ground for the head unit should be as short as posable and go right to the fire wall. If the Sony your using is driving the speakers (no additional amplifier) and it is a "high-powered" unit, it's a good idea to get the constant power directly from the battery. Run 10 gauge wire through a grommet in the firewall with a fuse at the battery. If it's not high powered, it's OK to get power right from the factory fuse box, or even better, off of the ignition harness. I usually don't recommend using the factory radio harness in older cars, and they usually won't have constant power anyway.
Dan M.

If your lucky like I was, there should be some unused female connections under the dash that you can plug into. Depending on the year, they should be orange (dash light wire). I pluged my tach and oil guage light in to this pig tail and have dimmer controll like the dash lights.

There are a bunch of plugs under there, that's for sure. I suppose I could check with a voltmeter and find out which varies with the dimmer adjustment...

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Jopapa while your in there terminate your speaker leads to a terminal strip in one side and the harness leads to the other this way you avoid having to cut the harness if you ever change the unit. Included 8 1/4 12V taps when new harness was constructed this wires directly to the switched igination side of the fuse block with independent fuse protection for all 3 circuits am currently using (gauges, radio,spare). Next project how to hang some speakers in the overhead and yet keep them hidden by the headliner...........Dave