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Mystery blue wire bypassing the NSS |
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7172AMX
AMC Apprentice Joined: May/20/2015 Location: South Carolina Status: Offline Points: 124 |
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Posted: May/13/2021 at 10:05pm |
Hi all,
Eons have passed and its time to make it safe to start. The car is scheduled into a movie shoot and stranger(s) will be driving my AMC. weird right. 72 Jav sst 360 auto, owned since 92 wiring is all factory. Seems all this time a phantom dark blue wire w/(white)tracer attached (factory crimped) along with the black wire (runs to ground terminal on the start sole.) at the engine harness side of the neutral safety/backup switch harness has a continuous path to ground, 56ohms to be precise. The switch works fine but its basically shunted to ground by this undocumented wire. It's nowhere to be found in the 72 FSM (schematic). I'm certain the NSS will operate proper if I cut this wire out. But what is its purpose? Where does it land? Appears to be running toward the firewall junction block. A nice citation for who helps solve and get the SST on the big screen! |
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GoPacKman
71 JavAMX 401 T-10 354TG 72 JavSST 360 727 315TG 98 Jeep Cherokee Classic 4.0 4WD |
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1970GroceryGetter
AMC Apprentice Joined: Apr/05/2021 Location: Detroit Status: Offline Points: 44 |
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From doing some digging, another gentleman was describing the function of the neutral safety switch on your particular car/trans and here Is what he said, let me know if this makes sense or helps clear up the extra wire or just muddies the waters: “ The way the center pole on the transmission switch works is it provides ground when in park or neutral. On my 73 the starter solenoid has power from the ignition switch in start position going to the S terminal on the front side. On the back side is a pole sticking out that goes to the center pole on the trans switch so when the car is in park or neutral, the solenoid has a complete circuit to operate.”
-Rudy
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troutwilly
AMC Addicted Joined: Sep/14/2007 Location: Carriere, MS Status: Offline Points: 994 |
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The diagram shows a wire labeled "Automatic Transmission Only". I would say that is your blue wire. Its obvious that the Tan wire provides the power from the fuse panel. Black is usually ground, but where does that black wire go in the diagram? The Brown wire is probably the one next to the Tan wire in the connector, but again, where does it go in the diagram? And what might the "DT" label on the brown wire mean? |
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Bill O.
70 AMX |
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7172AMX
AMC Apprentice Joined: May/20/2015 Location: South Carolina Status: Offline Points: 124 |
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Good questions. The NSS harness is 3 wire to the switch. The black wire runs back to the 1 pole connector back of solenoid. It's always grounded thru the mystery wire. That defeats the NSS, which checks out perfectly when isolated. Tan is +12 and brown is the lamp wire. I have to assume the "auto trans" note at the NSS is the normally closed (in park/neutral) switch to ground ala the dashed line in the diagram.
I appreciate the help and will likely use a toner to try tracing the mystery wire before I cancel it from the circuit unless someone can come up with it's purpose in life. These FSMs are never without fault, but I always figured the schematics were spot on. Always learning.
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GoPacKman
71 JavAMX 401 T-10 354TG 72 JavSST 360 727 315TG 98 Jeep Cherokee Classic 4.0 4WD |
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5458 |
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This is from Eddie Stakes site and it makes more sense with the color codes you have. |
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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7172AMX
AMC Apprentice Joined: May/20/2015 Location: South Carolina Status: Offline Points: 124 |
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Thanks Bee! but my eyes aint what they used to be and that ones a bit blurred. What year is that off?
I did find the Mystery wire's termination, got my toner on it today and it lands at this relay which i had no idea was there. it makes sense the relay aint on the schematic as this deals with the seat belt warning system, totally undocumented in the FSM. Not sure why the yellow pair is grounded which was the unwanted path to ground. pull off relay and problem solved for now. One fine day i'll restore the interior and get all the bells and whistles working too. Retirement cant come soon enuf.
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GoPacKman
71 JavAMX 401 T-10 354TG 72 JavSST 360 727 315TG 98 Jeep Cherokee Classic 4.0 4WD |
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5458 |
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Eddie's site says that is from 1974.
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4837 |
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I'm going to guess yours is a later 72 because that shows up in a 73 wiring diagram.
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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