Ford 5.4 and 4.6 Emergency Starter Solenoid Bypass

[Muckin_Slusher]

Hope this helps someone out of a jam someday.

I posted a while ago about my 5.4 starter not working. They have integrated solenoid. I crawled under the truck and shorted the big terminal to the "start" terminal. Nothing, starter would not run. So I shorted both big terminals and got the starter to spin, but not to engage the flywheel.

Problem is that the integrated solenoid both connects the voltage to the starter motor AND pushes out the little gear to mesh with the flywheel.

I don't want to have to change a starter in the snowbank in the middle of the bush. Luckily I kept trying it and it eventually worked. These starters aren't the easiest to change.

Back home, new starter installed.
I tested the bad starter, and sure enough the solenoid only engages occasionally.

I noticed a drain hole in the solenoid housing. Easy access when on the truck as the drain hole faces straight down. Yank out the plastic plug and use a scribe to pry the lever over and mesh the gear with the flywheel. Hold in this position while also shorting out the big terminals and the engine should turn over.

I did not test whether or not the truck will start with the key in the "on" position or if it has to be in the "start" position. If you're alone and it needs to be in the "start" position then you'll have to get creative to hold the key.

 

[Muckin_Slusher]

These views show how the solenoid work. At one end it makes the electrical connection, at the other end it pulls on this plastic plunger. Plunger engages with the plastic fork in the starter.

 

[[486]]

what it usually is on those specific ones is the solder disconnects from the little steel terminal strip with the m6 stud welded to it
try putting power to the little solder blob instead of the steel terminal, bet that solenoid clunks just like it should

ETA: also, if you mash the solenoid in far enough it'll operate the big contacts manually, so you wouldn't even need to jump them externally (unless they're actually burnt up internally)

 

[Derp]

This is excellent information to file away in the back of my head. I'll never know it's there unless I need it, then it'll be an "Ah ha!" moment that saves the day.

And I really like your fancy extended handle mexican-metric wrench there.

 

[Muckin_Slusher]

what it usually is on those specific ones is the solder disconnects from the little steel terminal strip with the m6 stud welded to it
try putting power to the little solder blob instead of the steel terminal, bet that solenoid clunks just like it should

ETA: also, if you mash the solenoid in far enough it'll operate the big contacts manually, so you wouldn't even need to jump them externally (unless they're actually burnt up internally)

Tried it. No luck.

I filed a clean spot on the body and pinched copper wire to ground the thing. I filed clean both globs of solder (the one connected to the steel plate and the one on the opposite side). I put (+) on all those locations.

I noticed when putting (+) on the little stud it would spark (proving current flow) and if I held it there then manually pushed in the solenoid, it would pull in and stay. Seems the coil is making magnetism, but the solenoid just doesn't want to start moving in.

 

[Muckin_Slusher]

This is excellent information to file away in the back of my head. I'll never know it's there unless I need it, then it'll be an "Ah ha!" moment that saves the day.

And I really like your fancy extended handle mexican-metric wrench there.

I call it my torque wrench.

I used to carry that one on my belt working underground as an electrician. I had a wrench holder made from sewn 2 inch ratchet strap webbing.

One day I was up an extension ladder. The ladder wasn't extended at all so it had parallel rungs right to the bottom. I was working by myself, climb down the ladder and kinda half rotate/jump off near the bottom.

Fucking wrench went between the parallel rungs and hung me just so my feet couldn't touch the ground.

There I am, hanging by my belt, hoping and swinging trying to get the ladder to fall.

Nobody saw.

 

[Muckin_Slusher]

I just doublechecked the part numbers, and the 5.4 V8 and 4.6 V8 both share the same starter motor, so same trick can be used.

Updated title as well.

 

[[486]]

Tried it. No luck.

I filed a clean spot on the body and pinched copper wire to ground the thing. I filed clean both globs of solder (the one connected to the steel plate and the one on the opposite side). I put (+) on all those locations.

I noticed when putting (+) on the little stud it would spark (proving current flow) and if I held it there then manually pushed in the solenoid, it would pull in and stay. Seems the coil is making magnetism, but the solenoid just doesn't want to start moving in.

notice how one of the blobs goes to the terminal that the starter motor brushes connect to?
That's the negative side of the meaty "pull in" coil
it uses the motor as the ground, then when the contacts make contact (when the plunger is fully in) and put power to the motor it then has 12v at both ends of the heavier winding, taking it out of the circuit. Smaller "hold in" coil holds the solenoid in all the way while cranking with a lot less current.

You'll see similar on big contactors and such. On those it is so that the contactor isn't drawing as much current (wasted electric, and excess heat).
On these solenoids it is about the heat, and the "break" current that the ign switch contacts sees, because it is DC so it'll arc the contacts out real easy. You'll see the same thing on starter solenoid contact ratings, they'll be rated for like 400A "make" and only 80A "break", because when the engine is overrunning the starter motor there's a lot less current going through the contacts, they can open with a lot less of an arc.

Try it wired up same as you did, but try also grounding the one big terminal that would go to the motor, bet it'll clack in just fine.

ETA: also, those old ford fender mounted solenoids? they were just a pull in coil with no hold in shenanigans, 'swhy they'd melt and start on fire if you've ever tried using them as a continuous duty solenoid.

 

[arse_sidewards]

I did not test whether or not the truck will start with the key in the "on" position or if it has to be in the "start" position. If you're alone and it needs to be in the "start" position then you'll have to get creative to hold the key.

It'll start with the key in on.

 

[Muckin_Slusher]

Try it wired up same as you did, but try also grounding the one big terminal that would go to the motor, bet it'll clack in just fine.

I tried this and it works every time. Put the starter back together with the motor wire back on that terminal, and it works every time when giving (+) to the little stud (grounding like you said through the motor).

Guess the problem could have been fixed by cleaning the motor to solenoid connection. Thanks for the help!

 

[[486]]

yeah, thing that sucks is that I can never get the solder to stick back to the steel S terminal
been meaning to try wrapping copper wire around the stud, and nutting it down for strain relief with enough of a tail on it to solder to the solder blob that has the magnet wires buried in it
haven't got round to it, had a good starter on the shelf to swap in...