Starter solenoid Pull-in and Hold-in coils explained and tested

[@carmelladean476]

I'm an engineer and have done a lot of training in my career. This is an absolutely fabulous presentation. I was looking for something like this to send to a young man who is working on one for the first time. Perfect.

[@g.j.dutoit4447]

Why if bench test ford ranger starter, it not stay ingage if i keep small wire on pin. It uningage with start small wire on start point. It must only uningage only when i take of start thin wire, am i right or wrong? Rrrrrealy hope someone can help me. Thanks guys.

[@g.j.dutoit4447]

It took so 6 seconds then it disengage with starter (key) wire still give power. Bendix gear turn strong. Then without take of starter wire it disengage and still turn fast. Not engage again. Is there something wrong with hold in coil?

[@g.j.dutoit4447]

I test my battery on load. Only drop so 1.5v on start. Its not battery

[@Hemojang]

Good job on the explanation! As a EE I also assumed it was just one coil, until I dug deeper. The design actually makes total sense, great stuff!

[@wyattoneable]

I like your drawing. It made it easy to understand. That was pretty tricky overlaying the scope on top the video.

[@arthurfricchione8119]

You are not the world’s greatest artist but you described the operation perfectly. Thanks buddy for sharing your knowledge and videos stay safe and well Artie 😊

[@billyyoder8171]

Thank you Chad and Val. Good job again. Have a blessed and safe week to you and your family.

[@shao8138]

Thank u Man This video really help me with the ASE questions

[@michaelwhelan564]

Excellent explanation. Thankyou. I never knew there were two coils!

[@ThePracticalMechanic]

I first learned about the two coils while diagnosing the starter on my Mitsubishi years ago. The hold in coil was bad so the starter would kick in and out rapidly at times. Thanks for watching.

[@hardeogangar6540]

thanks for letting me no it has 2 coils holding and pulling coil now i and fix my starter properly your explanation was great...

[@electronicproductcommercia5553]

Thank you so much, I'm testing a solenoid and needed a detailed explanation, I was assuming one coil and that it was grounded. That was obviously a wrong assumption. Great explanation!!!

[@spelunkerd]

The starter circuit has to be the best place to begin teaching auto mechanics. There are elegant design considerations that are rich with examples. Not only that, from a practical perspective, everybody will one day face a no crank, no start. The deeper you go, the more there is to learn about this circuit, thanks for the deep dive!

[@januario111torreon2]

Nice vid here, it helps me understand more about this component.

[@shamessun]

MAN THANK YOU..... that is a reallllllllllly good video

[@L-36]

Thanks so much. I have a starter problem on my boat and this helped a great deal in explaining what the solenoid does. My starter stays engaged even when I release the starter button. Hopefully the new solenoid I just bought will fix the problem. We shall see...

[@BigPete1911]

Great video

[@ThePracticalMechanic]

Glad you enjoyed it

[@RichardTowse]

Great explanation, thanks.

[@ThePracticalMechanic]

Glad it was helpful! Have a wonderful weekend.

[@joshuamyers3185]

😂🤣😂 great drawing but my mama says that the donkey that lives in the starter is how that thing works and when he dies time to get a new kicker device......great video man 👍👍👍

[@adigrecu7532]

Finally! This seemed like a well kept secret, but now I understand what and how to measure. Thank you!

[@Valamilk]

Smart, handsome, AND an artist??? Ooolala 😍

[@robzecc]

Great video! I have a 25A fuse in the starter circuit that is sometimes blowing. Other than that when it starts it start normally. What can be the problem? Do you think i can "safely" try and raise it to 30?

[@trusttshepomutonhori7518]

Thank you so much bro. My plunger is bouncing on the conducts instead of holding....what could be the problem

[@ImpanoBrice]

You are intergent

[@bushmaster777]

Thanks for explanation. I have a situation with my generator where the solenoid keeps the starter spinning after removing the trigger current. I was thinking if the solenoid may be getting self energized from the reverse current flowing through the motor contactors through the pulling coil and then onto the common trigger terminal and thereafter through the holding coil in series and getting grounded at the far end. What do you think? Are my return springs weak and not able to resist magnetism caused by two coils in series? TIA

[@ThePracticalMechanic]

Ive seen some small engine starter do the same thing when the gear is worn on the starter or if the start is too close to the flywheel(models with shimmed starters). Your idea may also be correct and would be made worse if the one way clutch on the starter gear is bad. Normally the gear is allowed to speed up with the flywheel after the engine starts but the starter can slow down because of the one way clutch. If the motor spins up as fast as the flywheel(magnified through the gear reduction it may turn the starter into a generator and possibly self energizing the coils in series. How do you currently get the starter to stop spinning?

[@bushmaster777]

@@ThePracticalMechanic Do you have an email id or Whatsapp number where I can send you a small video on the issue? I disconnect the battery to stop the starter spinning

[@danielmarkbuyoc9516]

Question: Does the electricity for the pull in coil go through the windings of the motor to go back to the battery (negative side)? If it does, won't it start the motor itself already because it has a little potential voltage going through it?

[@l4rn08]

yes the winding for the motor for pull in process will function as wire(negative).. But it not will spin the motor because the current from the pull-in winding not enough,, too little wire from winding pull in... like 2 bulb series in diferrent watt,, 100w and 10w bulb in series,, so the 100w will not turn on light,, just function as wire,, and the 10w will turn on light..

[@johnkanuchok]

Which scope software/equipment do you use in this video?

[@ThePracticalMechanic]

This was using the picoscope 6 software and 4 channel scope 4423

[@PandaBewok]

Brother, I still don't understand about the voltage potential difference, why is there no current flowing in the pull coil when it contacts 😌

[@PandaBewok]

why is 12 minus 12?

[@Richard012996]

Hi I just have a question from the Ontario Provincial truck and coach mechanic exam “a truck will not start, battery and alternator are found to be good, what is the issue” a) starter hold in windings will not engage flywheel, b) starter pull in windings will not engage flywheel, c) starter hold in winding stuck in flywheel, d) starter pull in windings stuck in flywheel. Highly appreciate it if I can get an explanation as well. Thank you!

[@ThePracticalMechanic]

It really depends on details. Does the starter click? Does it do nothing? Is there power to the big cable and small cable while trying to crank it? I would go with (B) if the pull in winding had failed the starter solenoid would not beagle to engage the starter pinion gear into the flywheel. (A) is incorrect because the hold in winding takes over and keeps the starter engaged after the pull in coil does the hard work. (C) is incorrect because windings won’t hold the starter engaged unless the engine is cranking (D) is incorrect the same way c(C) is incorrect. The electric windings just create a temporary magnetic field that pulls in on the metal rod that pushes the pinion gear or bendix in until it meshes with the flywheel gear. The magnetic field goes away when the key is released and if the starter stays engaged to the flywheel is will likely be a mechanical issue in the starter and not a winding issue.

[@Richard012996]

Thank you so much!!!