Need wiring help
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
Need wiring help
Swapped the bodies on the truck last weekend. Truck would not start, had to rewire the ECM. Now, truck starts, but does not shut off with ignition switch. In order to shut the truck off you have to disconnect the neg wire from the battery. I know the alt is not wired yet.
New ignition switch, third one... Eliminated as problem.
New solonoid, third one... Eliminated as problem.
I feel this is definitely something done in the wiring.
1977, 300 6cy, AT.
New ignition switch, third one... Eliminated as problem.
New solonoid, third one... Eliminated as problem.
I feel this is definitely something done in the wiring.
1977, 300 6cy, AT.
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
Checked that, doesn't seem to be the case.
Fleet Mechanic
Joined: Feb 2010
Posts: 1,742
Likes: 5
From: Near St. Joseph,MO
*missed it, just re-read.
There is only one way the truck stays running, the wire on the dist is still getting power. Does it start like normal? when it is off with the battery connected, is it draining power? Are you sure the wires are correct on the solenoid?
There is only one way the truck stays running, the wire on the dist is still getting power. Does it start like normal? when it is off with the battery connected, is it draining power? Are you sure the wires are correct on the solenoid?
Elder User
Joined: Sep 2014
Posts: 862
Likes: 7
From: like subarctic, brrr man!
What brian1080 said, but also check the ECM wire too with a voltmeter!
FYI, the coil wire should be attached to the I terminal on the starter solenoid/relay. It's what supplies full voltage to the coil for easy starts. And when running, coil is fed voltage through a resistor wire (about 8 volts).
The 3 wire plug:
1 wire (32 Red Blue) has power during start, and is the same wire that energizes the starter solenoid/relay.
1 wire (732 White) has power with ignition key in run.
If any of these are messed up, then you might have the symptoms you describe. If these wires are right, then the engine will stop when the key is off.
FYI, the coil wire should be attached to the I terminal on the starter solenoid/relay. It's what supplies full voltage to the coil for easy starts. And when running, coil is fed voltage through a resistor wire (about 8 volts).
The 3 wire plug:
1 wire (32 Red Blue) has power during start, and is the same wire that energizes the starter solenoid/relay.
1 wire (732 White) has power with ignition key in run.
If any of these are messed up, then you might have the symptoms you describe. If these wires are right, then the engine will stop when the key is off.
Posting Guru
Joined: Aug 2010
Posts: 1,761
Likes: 8
From: Knoxville, TN
Any other relevant details you haven't included yet?
If you pull the little wire off the S terminal on the starter solenoid, does it stop? If so, you've got a wiring problem feeding the solenoid or a bad ignition switch; if not, you've got a bad solenoid.
If you pull the little wire off the S terminal on the starter solenoid, does it stop? If so, you've got a wiring problem feeding the solenoid or a bad ignition switch; if not, you've got a bad solenoid.
Trending Topics
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
I will check all this tomorrow and get back to you guys.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
I and S cannot be switched, the truck will not start unless they are correct.
Posting Guru
Joined: Aug 2010
Posts: 1,761
Likes: 8
From: Knoxville, TN
Then, if you put the terminal that should go to S on I, it would be getting backfeed of +12V when the starter solenoid is activated; I'm not sure exactly how your wiring is set up, but there would be a feed from the ignition switch start position to the ignition module (and/or ECU in a fuel-injected setup) so that the engine can fire while cranking in order to start. Hooking the wire that should go to the S position to the I terminal is what supplies this circuit.
Easy enough to test whether that's what actually happened: swap 'em and see.
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
It should: the wire that should go to the I terminal ties in to the coil power feed after the resistor wire. If it gets hooked to the S terminal, then the starter solenoid will see ~8-9V when the ignition switch is in the run position - which should be enough to actuate it - so it'll be continually cranking with ignition switch in run.
Then, if you put the terminal that should go to S on I, it would be getting backfeed of +12V when the starter solenoid is activated; I'm not sure exactly how your wiring is set up, but there would be a feed from the ignition switch start position to the ignition module (and/or ECU in a fuel-injected setup) so that the engine can fire while cranking in order to start. Hooking the wire that should go to the S position to the I terminal is what supplies this circuit.
Easy enough to test whether that's what actually happened: swap 'em and see.
Then, if you put the terminal that should go to S on I, it would be getting backfeed of +12V when the starter solenoid is activated; I'm not sure exactly how your wiring is set up, but there would be a feed from the ignition switch start position to the ignition module (and/or ECU in a fuel-injected setup) so that the engine can fire while cranking in order to start. Hooking the wire that should go to the S position to the I terminal is what supplies this circuit.
Easy enough to test whether that's what actually happened: swap 'em and see.
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
As soon as you put it in the start position. Right now the alt is not hooked up, so the only way to shut it off is to pull the negative terminal off the battery or the S or I wire.