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72 AMX Wiring Questions

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    Posted: Dec/16/2018 at 5:55pm
OK AMC Gods...need some help sorting out the wiring harness on my 1972 AMX 360. The previous owner decided to remove the wiring harness from the engine compartment and didn't mark anything in the process.  I have a really blurry wiring schematic for a 73 AMX and think I have most things figured out, but need some guidance on a couple of things.

1.  On the start contactor (relay) I have a green/yellow wire with a 90 degree rubber boot connector on it that I believe plugs onto the "s" terminal of the relay.  Is this correct?

2.  Also I have a ring connector on a red wire that is harnessed together with the pink wire that goes to the Horn relay.  I believe this goes to the battery terminal on the relay.  Is this correct?

3.  I am not sure what alternator I have but it appears to be some no-name aftermarket job.  Looking at the rear I have the large red ring connector connected to the large post at the 2:00 spot, the orange spade connector hooked to the 1/4-spade on the terminal at 3:00, and the black & green angle connector to the terminals at the bottom.  It seems like there should be something connected to the terminals at 8:00 and 10:00 (sensing for the ALT light?) but I am out of wires except for a black wire with a 90 degree rubber plug connector...which brings be to my last question.

4) I have 4 90 degree rubber plug connectors.  I believe the purple one goes to the engine temp sending unit and the light blue goes to the oil pressure sending unit.  I have a black wire that I do not know where to connect and also a black/white stripe wire that comes out of the harness with the blower motor connector that I don't know where to hook.

I threw together some quick images to show what I am talking about below.  Tried taking some pictures but wire are so dirty it was hard to tell colors.  I plan to redo the harness eventually.

Thanks in advance for any help.


 









Edited by AMXrated - Dec/16/2018 at 5:57pm
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Edited by 304-dude - Dec/16/2018 at 6:35pm
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXrated Quote  Post ReplyReply Direct Link To This Post Posted: Dec/16/2018 at 9:23pm
Thanks 304.  Diagram is much clearer than the one I have, but seems to not show some wire/connectors I have.  Although, for all I know someone may have altered the harness over the years.

Also, I got your other response via email, but the message doesn't seem to be showing up on the forum.

I think the black/white stripe connector that is near the blower motor connection is for the brake warning light and connects to a sending unit on the brake line manifold.  I haven't put the brake system back in yet so I didn't notice it.

  

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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXrated Quote  Post ReplyReply Direct Link To This Post Posted: Dec/18/2018 at 7:27am
I have narrowed the mystery wires down to just 3 at this point.  I did test the ignition system by wiring an old starter up outside the engine and it did spin up (with no smoke anywhere).  It was actually kind of cool to see the dome light come on and hear the "don't forget your keys buzzer".  Here is what I have I have left--any help would be greatly appreciated.

1) Still not sure where the black wire with the 90 degree plug connector goes. Obviously designed to go on a #10 screw type terminal:



2)  I have three wires that exit the firewall above the main harness grommet.  They each have their own grommets.  There is a red, yellow, and black wire.  The red wire has a ring connector and I believe is the hot wire for the rear window defogger.  Looks like it goes to the battery side of the start solenoid.  No clue on the yellow or black:



3) There is a brown wire that exits the "headlight" harness close to the driver's side shock support.  Has a straight rubber lug connector that is designed to go on a #10 screw.  I don't think there are any components in that area to connect to:


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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Dec/18/2018 at 7:58am
I think some of your issues identifying your connections is that we have no clue to your car setup.

Is it a late 72?
Automatic?
A/C?


If it is an automatic, there will be a connection for temp controlled spark to port vacuum advance into the atmosphere. Its connection is at the location described in your last question.

Remembering my late my late 73,  there was a yellow wire through the firewall to a solenoid at the carb throttle stop.  It was for A/C cars.

As for the black wire with 90° plug... depending on proper starter solenoid. There should be a pin on the underside of the solenoid for park / neutral safety switch function. It keeps the starter from being activated when in drive gear range and reverse. Some use a Ford starter to bypass the option, or just don't know any better.

As for the red wire? It seems to have a non factory connector. Haven't got a clue to it, as I would need to see more of it. As in length and placement. 

I will be In the garage, and can pull my harness out of the box and look for such a wire, though it's a 71 harness, which will not have some all of the wires your 72 has.


71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Oops, sorry--guess that would be good info to include.  Car is a 72 P code AMX with a stock T-10 4 speed.  No A/C. Not sure about build date--last VIN digits are 176897. 

Sounds like the brown and black wires are not needed as it is a manual.

The yellow wire does have a heat shield on it, so it would indicate it goes near the exhaust manifolds somewhere.  Stock carb is missing and I have no A/C so sounds like the yellow is not needed.

Red wire is long enough to exit the firewall on drivers side and run across the firewall, along the pass side fender and reach the battery side of solenoid.  Has a 5/16 diameter ring connector on it.  Not at home right now but can post an image later if needed.

Thanks so much for the help!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Dec/18/2018 at 8:31am
Originally posted by AMXrated AMXrated wrote:

Oops, sorry--guess that would be good info to include.  Car is a 72 P code AMX with a stock T-10 4 speed.  No A/C. Not sure about build date--last VIN digits are 176897. 

Sounds like the brown and black wires are not needed as it is a manual.

The yellow wire does have a heat shield on it, so it would indicate it goes near the exhaust manifolds somewhere.  Stock carb is missing and I have no A/C so sounds like the yellow is not needed.

Red wire is long enough to exit the firewall on drivers side and run across the firewall, along the pass side fender and reach the battery side of solenoid.  Has a 5/16 diameter ring connector on it.  Not at home right now but can post an image later if needed.

Thanks so much for the help!

The yellow wire with heat wrap, does not mean it goes near exhaust manifolds. All single wires that are to be around the engine have the heat wrap. It is possible that a previous owner replaced the stock engine wiring harness with like out of a 72 automatic, or the factory had one harness for both manual and automatic Javelins.

Never seen a single red wire from firewall go all the way to the starter solenoid, as you described. Though I never owned a manual, or checked out a manual Javelin's engine bay wiring.

It may be a custom wiring job, as the diagram I posted pretty much shows all the connections. Though not all... you may need to climb under the dash and look for the wire entrance, and follow it. Most likely it is loose from the wrapped harness, and can be traced to its origin.

My 73 had a windows defogger,  and it was wired to the fuse panel not through the firewall.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXrated Quote  Post ReplyReply Direct Link To This Post Posted: Dec/18/2018 at 8:47am
OK, thanks.  Good info.   

Don't think the red wire is related to the manual as the only electrical connection on it is the back-up light switch.  I've read where some owners have added neutral lock-out switches, but I don't think they were factory (I could be wrong on that).

Yeah, I was going to contort myself under the dash tonight and see if I could trace the wires.  The previous owner did add analog gauges for oil and temp so the renegade wires may be for gauge lights.  Everything else appears to be stock--but wires may be left from whatever else might have been done to the car over the past 46 years.

I'll post an update if I figure it out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXrated Quote  Post ReplyReply Direct Link To This Post Posted: Dec/18/2018 at 3:25pm
I traced the red, yellow, and black wires that have individual grommets back under the dash.

The red wire goes into a relay mounted to the side wall under the dash. It also has 2 blue wires and a brown connected to it.  I see nothing on my schematic that shows this combo.  Based on the parts that American Parts Depot carries, it looks like a rear window defogger relay for a 75-78 Gremlin.  Here is an image of it:

I think this is what I am dealing with:



The yellow wire appears to go to a connector on the ignition switch.

The black wire goes to a connector on the tach/clock side of the instrument panel.  My guess is that it is for the tach and goes to the coil which probably explains the fork connector on the end of it. 

I am adding a D.U.I. HEI distributor which has an output for tachometer.  If the black wire is for the tach, can I connect it to the HEI tach output?  Or, will something bad happen?

Thanks.




Edited by AMXrated - Dec/18/2018 at 3:45pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Dec/18/2018 at 4:26pm
Ha! You lost me on the defogger... It is the rare defroster which is different. No wonder I could not figure out the red wire to the solenoid. That option is so rare on javelins that only a few here have dealt with the wiring.

As for DUI distributor,  basically the pulses are inverted, and may work with the tach you have. The pre 71 tachs have issues, as for peeps being careful. If not you can obtain a tach inverter to put the pulses proper for the tach.

I have an HEI and may do the inverter myself when I connect the tic toc tach.

Great to see you found it all on your own, now you can feel accomplished, as it is a true surprise, only second to finding a build sheet. 

I would have mentioned the relay and resistor... only if you said the rear window had a grid for the defroster. That would have helped on figuring put why you had separate wires to the fire wall.


71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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