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10/10/2014 6:59 PM  #1


Ignition wiring HELP!?! 1970 mustang

I have a 1970 Mustang I am trying to fix the wiring on that was pretty abused before I got it.  I've removed all the household wire nuts and direct to battery switches I could find and I'm starting over.

The problem is I can't find a wire off the ignition switch that has 12V in crank.  I want to find that so I can run it to my S terminal on my starter relay.  At the starter relay I have a big black wire that was spliced to the battery side of the solenoid.  When that is powered up I have a red wire with 12V in run, brown wire 12V in run and red/blue wire with 12V in run.  They all drop out in crank.

At the ignition switch I have a black/green wire 12V key on; Pink wire 12V key on; Yellow wire 12V key on; blue/red 12V key on; Purple 12V key on but drops out to nothing when in crank;  White/red with nothing coming out of it, but nothing is on the other side of the plug.

I did a lot of suff to the car at once. I installed a t5 but i spliced the red/blue wires together for the N safety switch.  I'm putting in a relay off the igniton to run a fuse panel which will power the HEI dist and the coil, I'm just trying to get it to crank.

Which wire goes to the S terminal for the crank signal and which wire off the switch sends it?

I have a wiring diagram but it doesn't show how the switch is wired.  Any help is appreciated.

Thanks,

 

10/10/2014 8:38 PM  #2


Re: Ignition wiring HELP!?! 1970 mustang

I may be wrong but, I don't think there is a wire off the ignition switch that does 12v in "crank" mode. That 12v in crank mode is coming from the starter relay terminal, the smaller terminal on the right (I) which should be a brown wire..

The ignition switch is connected to the starter relay smaller terminal on the left (S), with  red with blue stripe wire.  When the key is in crank mode, this wire pulls the contacts down within the starter relay and connects the battery to the starter via the two large terminal posts,  and it also connects the battery to the smaller terminal post on the right (I) which should be a brown wire that eventually leads back to a connector that is spliced with the pink wire from the ignition switch and then onto the coil.

When in crank mode, since those wires (brown and pink wire) are spliced together going to the coil,  brown wire feeds the coil in crank mode from the starter relay, while the pink wire from the ignition switch feeds the coil in run mode.

Last edited by MarkinSC (10/10/2014 9:07 PM)


GET HER DONE BULLETBOB!!! ..
 

10/11/2014 5:36 AM  #3


Re: Ignition wiring HELP!?! 1970 mustang

there is a red wire with a blue stripe in the back of the switch, this goes to the neutral safety switch then to the s post on the solenoid. this sends power to the solenoif in the start position. i would bypass the safety switch and connect it directly to the solenoid temporarily.

 

10/11/2014 6:31 AM  #4


Re: Ignition wiring HELP!?! 1970 mustang

Arden, a wiring schemetic is a must with your project! Buy one or you can find one on the net.
Howard

 

10/11/2014 8:23 AM  #5


Re: Ignition wiring HELP!?! 1970 mustang

My diagram shows a red/blue wire on the ignition switch plug right across from the pink wire.The red/ blue is used for cranking. Maybe you have a bad switch or that wire is missing. Also keep in mind the pink wire is a resistor wire used to supply 9 volts to a standard ignition.

Last edited by wsinsle (10/11/2014 1:33 PM)


If this forum can't fix it, it isn't broke.
 

10/11/2014 9:54 PM  #6


Re: Ignition wiring HELP!?! 1970 mustang

Thanks guys,  I got it figured out with your help.  The red/blue wire is the crank wire but I had 12V key on which was incorrect.  I figured it out:  It was backfeeding voltage.  Once I got that taken care of it was 12V in crank only.

Thanks for all your help guys-- except Howard

     Thread Starter
 

Board footera


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