i have a 77 150 4x4 .when i got the truck the previous owner put a 302 in the truck with the point distributor .needless to say they did some real shoddy work rewiring the point system into the electronic wiring harness they cut wires in the ign.switch ,at the solenoid,coil and did away with the module also running jumpwires everywhere.
i fixed all the cut wires and ran a wire to the coil from a keyed circuit.iplan to put an electronic dist back in but that a later post.
in order to start the truck i need to turn the key on and go under the hood and touch theterminal from the bat.hot and the small connecter closest the from battery terminal i believe the small connecter goes to the small brown wire,this wire is not recieving voltage
could the ign switch or the solenoid be bad ?

 

The I terminal gets the brown wire.

The red/? goes to the S terminal.

 

well upon closer inspection,my solenoid dosent have the I or S marks therefore the red wire is closest the battery .now when i jump this wire to the incoming + 6GA red cable and the key on the truck fires.understanding i fixed all cut wires returning the system back to original minus the module and running a keyed on hot wire.
what am i lacking or what could be defective?
obviously the red wire should be getting voltage on its own to open the circuit to the starter and obviously i have the run circuitry working properly

 

The circuit you are missing has a red/blue wire. This circuit starts at the ignition switch, where it get power when you spring the switch over to "start". The red/blue wire goes from the ignition switch to a neutral start switch. This may be a switch on the clutch pedal, or one on the automatic tranny linkage somewhere. From the neutral start switch, it then goes to the small terminal on the starter relay(the one you have been jumping).

 

ok. the red with blue is intact ,still no fire at key . i pulled down the ign. switch to check for voltage at the yellow wire and bk-g wire neither had voltage therefore no current to r-bl.however with the key still turned the truck will still fire when jumped off as earlier stated. i thought i was closed to figuring this out but i am slowly confusing myself

 

Well, find a source of power, and jump to the red/blue at the ignition switch. It should crank. I don't have a diagram that shows the different circuits feeding your ign switch, but you could take and jump to the yellow wire at the switch, and then turn the key. It probably would crank if the yellow wire fed the red/blue throught the switch. This might get you back on track.

 

The stock wiring is as follows:
The large yellow wire at the ignition switch is the main power feed wire.
The ignition switch connnects other wires to this wire thru the switch contacts.
In "start" the red/blue wire is supplied with 12 volts then off to close the starter relay.
In "run" the and "start" the red/green wire is fed 12 volts then off to the coil.
The black/green wire gets 12 volts in "run" and "acc" only.
So if you have to turn the key to "run" to get the engine to run when you jump the start relay....we can assume the ignition switch is getting 12 volts on the yellow wire.
So try removing the iginition switch and jumping the yellow wire to the red/blue wire.....if the starter turns probably a bad ignition switch....if it doesnt turn the red/blue wire must be open somewhere between the switch and the relay.
Of course since there was a lot of cutting and splicing done before you never know what is wired where.
You could connect 12 volts to one side of a momentary contact switch and connect the other side of the switch to the "S" terminal of the start relay.
Then you will have control of the ignition with the key and control of the starter with the new switch.

 

thanks,shouldnt the yellow be a constant hot,because i probed the yellow with my meter and got no voltage.
and the switch is an idea but i would rather find and fix the problem.ive got a feeling its open somewhere,maybe a fusible link eh? dosent the yellow come out and junction into a bk-y and then fuse link into the hot side of the solenoid?

 

Yes it should be constant 12 volts, as long as battery is connected and charged to 12 volts
My diagram shows black/yellow stripe from starter relay to factory splice then yellow wire from splice to ignition switch.
There is a fusible link on the wire end at the starter relay.
If you have to turn the key to "run" in order to get the truck to start by jumping the starter relay....then there should be power on the yellow wire at the ignition switch......unless there has been some "after-factory" wiring modifications

 

got it all figured out , thanks for the help.first thing wrong was the black and yellow from the relay was broke under the insulation. after fixing this i was able to get voltage at the ign switch on the yellow.the second problem was the R-B wasnt transferring the voltage . i traced the wire and found a 4 plug flat connector with 2 R_B and 2BK-R ,these wires were cut ,i am assuming some of those wires went to a saftey switch . what i did was pull an old wiring harness out of storage ,it came off a 74 truck and it had a return loop connector {they must not have used a saftey switch on the older truck}. when i plug this connector in the truck fired from the key

 

The return loop connector was used on manual transmissions when there wasn't a neutral safety switch. You just had to be careful not to start it in gear with the clutch out.

 

Congrats on the fix
The red/blue wires are for the neutral/safety switch and the black/red ones are for the backup lights switch.

 

thanks for the help sparky,i have every electrical problem fixed. i cant remember the last time i had an old truck that stll had working instrument,dome and cargo lights