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Starter won’t engage on key, only when shorting out relay

JKCuda

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I am desperately trying to fire this new motor and I’m beating my head against the wall. Installed a new American auto wire harness and a flaming river column that has the gm ignition switch. After speaking with American auto wire I have it all figured out now but I can’t get the starter to run on the key. I can short the relay out and it runs the starter no problem. I have 12v on terminal I and 12v on terminal G when the key is advanced to the start position. Shouldn’t this activate the relay and kick the starter off???
 

JKCuda

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So I grounded out G to the body and the key works now. So bad neutral switch? Why would I be seeing 12v on it?
 

Chryco Psycho

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The 12v will close the relay if it has ground as you found out .
the Ground wire should go the center position on the NSS & ground through the trans in N & park [Auto trans] there should not be power on that wire , something is connected wrong .
 
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JKCuda

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The 12v will close the relay if ti has ground as yu found out .
the Ground wire should go the center position on the NSS & ground through the trans in N & park [Auto trans] there should not be power on that wire , something is connected wrong .
Yeah I’m starting to gather that. I’m jammed up at this point because the center wire is 100% running to the starter relay as the ground and the outside wires are hooked as the auto wire instructions show. I tried reversing the outside wires to see if it made a different but it doesn’t. One is pink for 12v ignition, the other green for backup lamp. They both come right out of the bulkhead so I can’t figure out where I might’ve screwed something up.
 

Challenger RTA

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Pink? I think you mean light red.

engine_wiring_web.jpg
 

JKCuda

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Dropped the pan and pulled the plug. The selector and detent was all out of whack. Park on my shifter was actually reverse and reverse was neutral. Fixing now…ugh.
 

MoparCarGuy

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So I grounded out G to the body and the key works now. So bad neutral switch? Why would I be seeing 12v on it?
To answer your questions and shed some light on the Starter Relay function...

The Ignition (12V) from the key switch powers the Starter Relay internal coil when grounded by Terminal G (Neutral Safety Switch - NSS).
The internal coil for the Starter Relay is the load. Without a ground (GND) the voltage passes through the coil and your meter shows 12 VDC on both I and G terminals. Once grounded, the coil energizes and terminal G to GND then becomes 0 VDC.
The electromagnetic coil then closes the normally-open (NO) contacts and connects battery (BAT) voltage to the Starter Solenoid (ST SOL).

Shorting BAT to ST SOL bypasses the relay's normal function and energizes the Starter even if the key switch is turned off.
The engine will not start without the key switch in the RUN position because you do not have power for the Ignition system.


Starter Relay Diagram.jpg
 
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Challenger RTA

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What an experience!

The mystery of life is not a problem to be solved, but a reality to be experienced.​

Only in a perfect world we are not challenged.
 

MoparCarGuy

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For reference, this diagram provides the steering column wiring with the engine compartment start circuit and Neutral Safety Switch (NSS) wiring.

Ignition Switch and Steering column harness.jpg
 
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JKCuda

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Appreciate that information, very informative. So we dropped the trans pan and valve body because we could see a lot of excess movement and what we found was I was missing the washer and c-clip off the shift selector, which allowed it to move up and down and come out of place against the detent pin or whatever it’s called. Also, that’s why the wiring and stuff seemed all wrong because internally the shift selector was never in the right spot. So, gotta order a washer, c clip, and maybe a new shift selector and arm because it’s pretty apparent the old one was bent out of shape by the last owner, the button it all back up.

What a day…
 

Challenger RTA

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I don't think it is. If it is a special size make it from a stand washer. been there done that. Don't worry it will show up after your done!
 

JKCuda

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Actually had the small seal, must have come in one of the kits I bought when I rebuilt the trans. One trip to Lowe’s and now we’re back in business!

IMG_1821.jpeg
 

JKCuda

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Got it all back together...went to fire it...spewing fuel out of the bottom of the accelerator pump. Brand new Holley 750 double pumper. I just can't catch a break.......
 
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