Need help with wiring grill lights

[jowens1126]

Well after several long hours of wrenching, we finally got the new mach 1 grill installed.  It came out very nice.



I got the 72 style grill mounting bracket from Don at OMS.  Its nice to have someone that seems to be able to find just about any original part you need.

It was not as easy as it looks to mount this new grill.  We had to unbolt the back bumper bolts and loosen the front bolts so it would drop down to get the old grill out and the new one in.  Then to get the mounting bolt holes to line up around the head light, we had to pull HARD in multiple directions to flex the tabs to where they lined up properly with the holes.  Only 3 out of the 4 holes actually lined up, but that should be plenty.  The center bracket was a snap.  I just didnt like the tiny little screws that were originally used, so I drilled the hole out a tiny bit in the grill so it would fit a larger 1/4-20 bolt.  Then I replaced the U nut on the grill bracket to 1/4-20 and it screwed right on.  I did have to drill a new hole in the bottom of the core support to attach the bottom of the center bracket to the core support.  I just used a self tapping screw.  Worked out great.  Of course to drill the hole, we had to remove the lower stone guard body panel, which was completely rusted on, so we could get the drill at a decent enough angle to drill a pilot hole.  But it all worked out.  Miraculously, the hood latch lined up correctly on the first try.



gif hosting

My question is, what is the best way to wire up the grill lights.  The sockets that I got, which were recommended by several members here, have 3 wires.



Looking at the wiring diagram, it only shows 2 wires.  So I am somewhat at a loss right now on what to do.  Does anyone know exactly what each wire does?

Here is the overall Lighting circuit diagram.



Here is a zoom in of the headlights and the grill lights.



Tracing the Yellow Power wire(478) back to its origin reveals that it goes to this 3 prong connector.  The 3 prong connector is a mystery to me.  Another mystery is Wire #15, which is also pinned in to the same pin on the 3 prong connector, but it goes over to this rectangular box.  Does anyone know what the rectangular box represents?  What #15 is? 



I am wondering what the 3 wires on my new socket do compared to the 2 wires shown on the diagram.

Then I am also wondering if I can tie these grill lights into the headlight circuit.

If So should I run the Yellow wire to the Red headlight wire or the Green Headlight wire?  I want them to be on with both high and low beams.

Any help would be fantastic.

Thanks in advance guys!

Jim

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[midlife]

Well after several long hours of wrenching, we finally got the new mach 1 grill installed.  It came out very nice.

I got the 72 style grill mounting bracket from Don at OMS.  Its nice to have someone that seems to be able to find just about any original part you need.

It was not as easy as it looks to mount this new grill.  We had to unbolt the back bumper bolts and loosen the front bolts so it would drop down to get the old grill out and the new one in.  Then to get the mounting bolt holes to line up around the head light, we had to pull HARD in multiple directions to flex the tabs to where they lined up properly with the holes.  Only 3 out of the 4 holes actually lined up, but that should be plenty.  The center bracket was a snap.  I just didnt like the tiny little screws that were originally used, so I drilled the hole out a tiny bit in the grill so it would fit a larger 1/4-20 bolt.  Then I replaced the U nut on the grill bracket to 1/4-20 and it screwed right on.  I did have to drill a new hole in the bottom of the core support to attach the bottom of the center bracket to the core support.  I just used a self tapping screw.  Worked out great.  Of course to drill the hole, we had to remove the lower stone guard body panel, which was completely rusted on, so we could get the drill at a decent enough angle to drill a pilot hole.  But it all worked out.  Miraculously, the hood latch lined up correctly on the first try.

gif hosting

My question is, what is the best way to wire up the grill lights.  The sockets that I got, which were recommended by several members here, have 3 wires.



Looking at the wiring diagram, it only shows 2 wires.  So I am somewhat at a loss right now on what to do.  Does anyone know exactly what each wire does?

Here is the overall Lighting circuit diagram.

Here is a zoom in of the headlights and the grill lights.

Tracing the Yellow Power wire(478) back to its origin reveals that it goes to this 3 prong connector.  The 3 prong connector is a mystery to me.  Another mystery is Wire #15, which is also pinned in to the same pin on the 3 prong connector, but it goes over to this rectangular box.  Does anyone know what the rectangular box represents?  What #15 is? 

I am wondering what the 3 wires on my new socket do compared to the 2 wires shown on the diagram.

Then I am also wondering if I can tie these grill lights into the headlight circuit.

If So should I run the Yellow wire to the Red headlight wire or the Green Headlight wire?  I want them to be on with both high and low beams.

Any help would be fantastic.

Thanks in advance guys!

Jim

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There is no reproduction 2 wire sportslamp socket, so the three wire one is used.  Simply ignore the black wire (ground) as it is not used; it goes to the metal prong on the side. 

To wire it correctly, you need to tap into the orange/red wire on the dimmer switch (inside the passenger compartment, wire 15).  This gives power whenever the headlights are on, regardless of low or high beams.  The other wire is black and is your ground.  

The yellow wire with three outgoing lines is an internal splice in the underdash harness.  You normally will not have access to it.

Hope this helps.

 

[jowens1126]

Midlife,

What is The square box on the diagram where 15 goes to?

I'm also a bit confused. There are red, brown and black. You said don't use the black, then you said black is ground.

 

[midlife]

The box-like structure is the headlight harness connector that goes to the back of the fuse box.

I'm sorry; my wire colors are from the headlight harness. Just use the two wires that go to the two interior pins of the lamp socket and ignore the outer pin (which is typically black).

 

[jowens1126]

ok thanks, that helps alot!

Another question on the headlights.

When the brights are on are both the red and green wire energized?  I know on some vehicles, the brights are when both elements are powered.  If that is the case, I could wire right in to the red wire right by the headlight and I wouldnt have to worry about running a wire to the interior.

 

[midlife]

I don't believe so with single beam headlights. I believe they use different filaments; I know that the dimmer switch switches from one to the other.

 

[OMS]

ok thanks, that helps alot!

Another question on the headlights.

When the brights are on are both the red and green wire energized?  I know on some vehicles, the brights are when both elements are powered.  If that is the case, I could wire right in to the red wire right by the headlight and I wouldnt have to worry about running a wire to the interior.

Headlight lights are switched.

How about tapping into the side marker lights

That way they are on with just the parking lights and when the headlights are on too.

I don't think the small power draw of two lights would bother the flashers

 

[jowens1126]

Thanks Don. I May try that.

 

[mudbilly]

I don't know if the 73 version or the Mach I grill lights are different, but my car has 3 wire connection and 3 wires going into the harness. I assumed that it had to have this in order for them to also work as turn signals?

The grill lights an side lamps come on with the headlight knob pulled out half way (I guess they are considered driving lights ?) and stay on with the knob out all the way.

Just curious as I have been following this thread and finally had to go look at my car to make sure I remembered correctly.

 

[midlife]

73 sportslamps are different: they contain turn signals and running lights separately, and need the ground line for the two filaments. 71/72 bulbs have only one filament.

 

[mudbilly]

Where are the front turn signals in this  setup ?

 

[midlife]

1973 turn signals are only in the sportslamps. 1971/72 have separate turn signal lamps up front (I think under the bumper), sharing running lights and turn signals.

 

[jowens1126]

I finally got around to getting the grill lights working today. It was pretty simple. I wired them in with the side marker lights as Mid-Life Suggested. Worked out great!

Light wiring

Grill - Lights off

Lights on

Overall I think it came out great.