77 f250 wiring

have 1977 f250 camper special, wiring has been hacked up, wiring diagrams i have found and spent $ for dont work fully for this truck ie.. 2 starter silinoids. main one next to battery leads to 2nd one on drivers side and 1 wire from that one leads under dash just dangling. think thats why it wont start but can't find diagrams with the 2nd silinoid. Thanxz wildratt

Not sure what you have going on there. But you only need one solenoid switch. The switch should have two big bolts and two small bolts.

A big thick wire goes to one of the big bolts on the solenoid switch from the battery, and the other big bolt a thick wire goes to the starter. Doesn't matter which order.

The small bolts on your solenoid switch, should have one with an s and one with an i.

The only important one here is the one with the s.

You need to feed your wire that is hot coming from under your dash with the ignition turned all the way over to start to that bolt on the solenoid marked s.

And make sure that the bracket on the solenoid switch is mounted tight and grounded well(tighten it down, then check with a test light from the bracket to the positive on the battery), if it lights it is grounded.


The way the solenoid works is like a relay, you energize a coil inside, with the wire going to the s terminal on the solenoid when the key is in start, and then the contacts close, allowing current flow from the one big wire to the other that is going to the starter.

the second starter relay has a right and left large post but only has 1 small post inbetween labled "s" the "i" is labled next to it but no terminal

Yeah, like I said you don't need to worry about the one that has "i" anyways, some of them do have a bolt there but either way you don't need to worry about that one.

Hope everything I told you so far gets you going though. If you want to do the job right, if there is a normally open switch that closes when you press your clutch down, wire that in b/t the wire going to your bolt with the s, That way you can't start the truck unless the clutch is pressed down. That's if it is a straight drive.

Also too anymore questions just write back I'll try to add some if I missed something or maybe someone else can describe how to do it better than me.

I used to own a 77 Ford F-250 Camper Special until roughly five years ago when I finally sold it, I believe that "I" terminal goes to the + terminal on the ignition coil and provides power to it while you are cranking the engine, then once you let go of the key the regular wiring provides power to the coil. I might be wrong its been a while.

I used to own a 77 Ford F-250 Camper Special until roughly five years ago when I finally sold it, I believe that "I" terminal goes to the + terminal on the ignition coil and provides power to it while you are cranking the engine, then once you let go of the key the regular wiring provides power to the coil. I might be wrong its been a while.

You are exactly right, if it's a ballast ignition coil, he may have one and I'm not sure so I'm glad you brought that up. If it's a not ballast ignition coil there is no need to worry about this.

The way it works is this, the ballast type gets like 6 to 9 volts from the ignition switch through a resistor wire, but yet uses 12 volts at startup to provide easier starts(hotter spark from coil), and that is the purpose of the (i) terminal on the solenoid switch. The vehicle can still be started without it but it's nice to have because the hotter spark makes starting easier.

He can find out which type he has by simply turning on his ignition switch, and checking voltage to the positive side of his ignition coil with a volt meter. If it's 12 volts then he doesn't need to worry about the (i) terminal. If it's 6 to 9, he needs to also make sure that there is a wire from the (i) terminal to the positive on the ignition coil to provide 12 volts at startup. He said his didn't have the bolt there on his solenoid though so I'm assuming that his is probably the non ballast type coil.

Hope that helps.