Starting Problems

[Fisherleep]

I replaced my hacked up 69 wire harness with a good used 75 wire harness because the old harness the previous owner had cut it all up and converted it to an electronic ignition also dropping in a 79 302 it ran if you wiggled the wires just right so I got the used one. My problem is that when I turn the key nothing happens, there is a new starter motor relay, ignition switch, ignition key and cylinder all wire are connected correctly that I know of checked many times, good ground. I have a manual on the floor and the 75 harness is from an automatic does any one know if that could be the problem because I don't have a neutral safety switch hooked up to anything? Is that why it does not want to start because it thinks its in gear? If so should I get a switch to plug into the harness to trick it to think it's in park or is there a way to cut the plug and connect wires into fooling it if so what colors? Any other opinions of what could be wrong will greatly be appreciated

 

[Seabronc]

That neutral safety switch will sure prevent it from starting. It is in series with the wire from the start position to the solenoid. If your truck doesn't have such a thing I'd bypass it. That is the wire that goes down to the transmission.

Have you tried a jumper from battery pos to the small post on the start solenoid? If that works there isn't much else between the key and the solenoid. I don't have a wiring diagram for your truck, but usually you have a circuit that is attached to the battery side of the start solenoid, thru a fusable link, perhaps some connectors, the column start switch, neutral safety switch and back to the small post on the start solinoid. If nothing happens when you turn the key, somethng in that path is bad.

The problem could be a misadjusted start switch mounted on the lower part of the steering column, a connector, etc. However, if you don't have that switch and it is not jumpered, it is most likely is your problem.

Good luck,

>-

 

[STLKIKN]

The neutral safety switch and the back-up light switch for a '75 Bronco are the same switch.
The factory plug will be on the firewall just above the intake. (if the "new" harness is installed exactly as the old one was.)
Look for a square black plug with four terminals. Two terminals will have the same color wires. They will be red with blue tracers.
Jump those two terminals.
With any luck, you have now found your gremlin....
Don't cut the new harness to permanently jump the wires, find a factory manual transmission truck of the same era. The harness will have a jumper built into the plug that will also have wiring that you can adapt to your 75 harness for back-up lights.
This is the trans side of the plug...