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Discussion Starter · #1 ·
Hello,

I just purchased my first 68 Firebird. The person I purchased it off of started taking the wiring apart in the engine. Currently when I turn the key absolutely nothing happens. From what I can tell I think it is the solenoid wire to the maxi Fuse. There is no Red 8 gauge wire running from the Solenoid to the maxi fuse. When I look at the Maxi fuse ( or what I think is the Maxi Fuse ) It looks untouched and when I trace the wires from the it, One runs to the fuse box under the driver seat and the other to the Alternator.

Can anyone help here? Or let me know where the Maxi Fuse is?

I also have a red wire running from the Neutral safety switch into the engine bay and it has been cut and not sure where it connects.

I am lost and trying to get power to the car and engine. Any suggestions would be greatly appreciated. I have attached a few pictures.
 

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Unless your 68 has been updated with a aftermarket wire harness, there are no maxi fuses. 1st gen tech section will have 68 wiring diagrams and 69 pontiac service manual to help you.

The way GM wired cars back then, Battery positive cable goes to starter, alt, and fuse box to power live all the time circuits. There will also be a wire going to ignition switch and headlight switch.

When ignition switch is turned to on, there will be several wires with key on power going to fuse box, ignition components, etc.

With key in start position, wires going to neutral safety switch of shifter, Then maybe to a start relay, and finally on to solenoid of starter.

On alt, there is a big, live all the time, power wire. And if alt is original 68, there will be wires going to an external voltage regulator.
 

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Discussion Starter · #3 ·
Thank you for al you're help here. I have checked all the wires and have been checking the voltage to all the wires. The car has power, The head lights and tail lights will turn on, but still when I turn to start the car nothing happens. The solenoid doesn't click or anything. I checked the " S" ( purple ) wire from the solenoid to the started and there is no voltage to this wire. I think It might be this wire and the NSS not getting power to allow the car to turn over. Any suggestions here?
 

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Start at the ignition switch. I believe 68 ign sw is in dash, if I remember correctly. Looked at 68 diagram. A purple wire comes out of ign sw. See if that wire has power with sw in start position. If no, ign sw is bad. If yes, move on to neutral safety switch.

. The output from the ignition switch goes to to neutral safety switch on the purple wire. With shifter in park or neutral, power should be on the output wire of neutral safety sw. If no, switch is bad or adjusted incorrectly. If yes, then fault is somewhere further down the line.

The purple wire out of neutral safety sw goes to starter solenoid.

Forgot to add, on 1st gens, there's a big plastic junction box on the firewall that all the forward wiring goes through. There could be a problem with wire connections there. And that could cause signal to starter to get lost. So, if you have power coming out of neutral safety sw with ign sw in start position. And you have no power at purple wire at solenoid, you have either bad wire or bad connection at junction box on firewall.

If you need them, I have 68 wiring diagrams in color I could send you. PM me with your e-mail address if you want these.
 

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Try these.

http://thefirstgensite.com/html/68wirindex.html

Purple with white tracer from ignition switch, supplies power (key on in start position) to the neutral safety switch. If neutral safety switch is working and adjusted properly, it will go through the switch to the solid purple wire and back to bulkhead connector in the firewall in front of the Ebrake assembly. It exits the bulkhead connector on pin L (top left when looking at the firewall bulkhead from engine compartment). From there to S pin on starter. This wire will ONLY GET POWER in the START position. No power exists here in the KEY ON/ENGINE OFF-RUNNING mode.

If you have no 12v coming out of the purple wire inside the car, jumper the two heavy gauge wires together at the neutral safety switch (temporary fix) to eliminate it as a problem.

Main supply voltage gets fed straight from battery thru a little junction block on the core support, to the voltage regulator. There will be a stack of wires or wires (heavy gauge) joined together by a bus bar at the voltage regulator. 1 goes to firewall block (cabin supply voltage), 1 more to the horn relay, and 1 more to the back of the alternator (output). These are all CONSTANT 12v.

Unless your restoring your car, I would strongly recommend converting over to the 1 wire alternator system. This will eliminate the finicky voltage regulator setup and clean up the engine bay. I have converted mine already and it was super simple.

Not sure but guessing someone has added the red wire on your neutral safety switch? Does it look factory installed or cobbled together?
 
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