Where is the "start" wire???
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Senior User
Joined: Apr 2006
Posts: 403
Likes: 1
From: NW Mississippi
Where is the "start" wire???
Tried to get the 390 rebuild fired up today but ran into a wiring problem... We've found the wire which supplies constant power to the coil but not the "Start" wire. The wiring diagram shows this second wire going to the dist. but not where it comes from. We ran a voltage tester on every wire we could find but found nothing. It's possible it has been removed as the truck was in pieces when I got it.
Where does this wire come from? Firewall? Celenoid?
Any help would be appreciated. Thanks.
spots
Where does this wire come from? Firewall? Celenoid?
Any help would be appreciated. Thanks.
spots
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
It comes from the solonoid. Look at the solonoid closely, if it has 2 small terminals, one comes from the key to close that relay, the other is the "start" wire that runs parallel to the ignition wire at the coil.
If your particular solonoid has only one small terminal, run a wire from the cable that goes between the starter and the solonoid.
A couple things to keep in mind: The ignition runs through a resistor (usually the wire it's-self on a Ford) and you should see (I think) 5 to 9 volts with the engine running. The start wire is a straight run and delivers a full 12 volts to get the beast started. If you were to maintain the full 12 volts on the ignition wire, you'd be changing points often.
HTH
If your particular solonoid has only one small terminal, run a wire from the cable that goes between the starter and the solonoid.
A couple things to keep in mind: The ignition runs through a resistor (usually the wire it's-self on a Ford) and you should see (I think) 5 to 9 volts with the engine running. The start wire is a straight run and delivers a full 12 volts to get the beast started. If you were to maintain the full 12 volts on the ignition wire, you'd be changing points often.
HTH
Last edited by Hypoid; Dec 23, 2007 at 11:56 PM.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Originally Posted by Hypoid
It comes from the solonoid. Look at the solonoid closely, if it has 2 small terminals, one comes from the key to close that relay, the other is the "start" wire that runs parallel to the ignition wire at the coil.
If your particular solonoid has only one small terminal, run a wire from the cable that goes between the starter and the solonoid.
A couple things to keep in mind: The ignition runs through a resistor (usually the wire it's-self on a Ford) and you should see (I think) 5 to 9 volts with the engine running. The start wire is a straight run and delivers a full 12 volts to get the beast started. If you were to maintain the full 12 volts on the ignition wire, you'd be changing points often.
HTH
If your particular solonoid has only one small terminal, run a wire from the cable that goes between the starter and the solonoid.
A couple things to keep in mind: The ignition runs through a resistor (usually the wire it's-self on a Ford) and you should see (I think) 5 to 9 volts with the engine running. The start wire is a straight run and delivers a full 12 volts to get the beast started. If you were to maintain the full 12 volts on the ignition wire, you'd be changing points often.
HTH
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
If the solonoid cranks the engine, it's working. If it's not cranking, put the start wire in the other terminal to see what happens. This won't hurt anything because the ignition terminal is energized only when the solonoid is pulled in.
So Bear was right about not hooking a wire to the starter cable, the solonoid isolates that terminal when it's open. Amazing what I remember when I read the manual.
If you get the solonoid to click, disconnect the starter cable before trying to measure any voltage outputs.
So Bear was right about not hooking a wire to the starter cable, the solonoid isolates that terminal when it's open. Amazing what I remember when I read the manual.
If you get the solonoid to click, disconnect the starter cable before trying to measure any voltage outputs.
Senior User
Joined: Sep 2006
Posts: 162
Likes: 0
From: Newbury Park Ca.
Hot?
Originally Posted by Bear 45/70
Not a good idea to run the hot start wire to tie into the large starter wire, as there is voltage on that start wire anytime the key is on. Better to change the solenoid to the right one. You can tie to the large starter wire only if you put a diode in between the start wire and the starter wire.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Originally Posted by aMoneypit
Are you saying the cable going to the starter has current in the "run" position?...........Why doesn't the starter stay engaged?.........aMP
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Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
Originally Posted by Bear 45/70
No, the start wire has power on it any time the key is in the run position, if the coil has power to it, so does the start wire.
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Postmaster
Joined: Aug 2005
Posts: 2,760
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From: Gadsden Purchase
Originally Posted by CN Spots
My solenoid has the two terminals but neither has fire when the key is in the start position. Bad ignition switch?
2) Keep doing that until it starts! :)
That's how most guys do it. :)
Don't want to be different do ya? ;)
3) If you point at a new electrical part you just changed out, buy another one because that new one might be bad. ;)
Remember when auto parts places wouldn't take back any electrical parts?
4) Or much more boring-and-nerdy... buy an analog meter from Radio Shack and find the trouble -while it's failing- and only repair or change out the bad part?
Naaaaa. :/
Alvin in AZ (retired RR signal-ape)
ps- don't know how to use a meter? :)
pps- ask here and those that know, will teach you, it ain't hard to use!
ppps- an analog meter is slightly cheaper and a much better tool than a digital ...for trouble shooting (and don't argue, i don't want to go through that again;)