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Texmach1

New member
Joined
May 11, 2019
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Location
Texas DFW
My Car
1971 Mach1

[url=https://ibb.co/7b7S3D9][img]https://i.ibb.co/fQmX3Wc/Mach1.jpg[/img][/url]
71 Mach one. I had a loose automatic shifter so I took it out to replace the bushings. They were missing. I accidentally broke the neutral position safety switch for the fmx trans. Did got a new one and installed it. While I was waiting for those parts to come in I change the point to PerTronix II and flame thrower II. Then when it was back together I turned the key.... power to the dash but nothing else, no click no start. I replace the solenoid relay and the ignition switch. Still nothing. I checked the continuity of the NSS and it was good when in the correct position. No power at the s terminal of the solenoid when cranking. I jumped the solenoid hot post to the s post and the starter cranked. I cleaned the ground to the battery and made sure that was good. No change. Not sure what the next step is, but it ran before I went to change those bushings. I would appreciate any help here. Thanks

 
Make sure you are getting 12 volts into and out of the NSS when the key is in start and transmission is in park or neutral.. You may have to trace the start wire (red with light blue stripe) from the ignition switch to the starter solenoid, until you find where there is no longer voltage.

 
I checked the four pin plug that the NSS plugs to at the fender wall. No voltage there. Is that the power supply to the NSS? . I have power at the I post of the solenoid with the ignition on. Is this supposed to give power to the plug for the NSS or only when trying to crank the ignition. I will have to chase the red/blues wire tomorrow. Battery still has 12 volts. I also could not get any voltage at the NSS cranking the ignition at any position. So it sounds like maybe the NSS is not getting power.

 
I signal is for the coil and unrelated to the starter switch.

Red/blue wires are the neutral safety switch wires, and the female side of the plug coming from the headlight harness side should have 12V when cranking.

My guess is that your new NSS/BU switch needs adjusting.

 
Attached is the 71 wiring diagram.

Page 3&4 are the charging & starting circuits. The male bullet of the two red/ lt blue stripe wires on the engine bay harness side of the NSS connector is the power in to the NSS for starting. With the key in START, it should have 12V. You can bypass the NSS by jumping it to the other red/lt blue stripe wire. This eliminates the NSS from the equation. If the car still won't turn over, you have problems elsewhere. I would start with verifying a solid battery->apron ground->engine block ground path. Many aftermarket ground cables omit the apron ground strap.

1971_full.pdf

 

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