Engine How does my solenoid work? Unable to start.

[Rivets]

It's not that hard if you have patience and don't let people confuse you, by getting out of sequence. This is one time where to many cooks spoil the soup. What people don't understand is that they are not paying is product, but time and experience.

 

[exotion]

It's not that hard if you have patience and don't let people confuse you, by getting out of sequence. This is one time where to many cooks spoil the soup. What people don't understand is that they are not paying is product, but time and experience.

Ya I think the patience is my downfall with electrical so far I've been fortunate and all my electrical problems have been obvious like broken wires. Seems like people just littlerly need to start at the battery follow the wires and find where the electricity stops

 

[Mad Mackie]

The first thing that I do is find and print the wiring diagram, I then enlarge it in portions on my printer and put the sections back together.
The flow of electricity is like water in plumbing. You need to find the initial source and trace each circuit from there. No wiring diagram is totally complete, so I add in the missing items on my enlarged diagram, for example, the battery, the specific engine electrical adapter and the charging system output connection to the terminal on the keyswitch as Scag and other manufacturers don't show this for some reason. As one becomes familiar with Scag electrical systems, the function of the electronic control module becomes more evident and I make notes to these functions on the wiring diagrams.
While in the US Army, I taught aircraft maintenance as part of " additional duties assigned", I learned very soon that I had to start with basic math/algebra before going into basic electricity. And I had to drop algebra from the course title and just call it Basic Math as the word algebra was intimidating to some students. I would work in basic algebra during the course and then tell the students that they now have already been using basic algebra. Then go into basic electricity and get out the aircraft wiring diagrams, and take them out to the actual aircraft to see the actual wiring. Their confidence and skill levels would improve which was gratifying to me as an instructor.
Then we got into hydraulics and with already having math and electricity behind them, hydraulics came easily to most of them.

 

[Fish]

Yeah, good advice. Pick 1 cook and stick with him......

Scags have relays and a control module that is most times the culprit, but that module is @ $100....

If the relays are all the same, swap them around and see.

Just for fun, try to get the engine to start by manually sending the voltage to the starter and solenoid, and see if the mower functions normally otherwise, check out the
safety switches that way.

The great benefit of working at a Scag dealership, is that the techs can grab a module, plug it in, and see if it cures the problem. If it doesn't, then they unplug it,
and put it back on the shelf, and try something else. But most times, it was the stupid module.... Or a relay...
If a customer buys that module, it is his, he cannot return it....


But find that cook that knows how to BBQ a big Scag..........

 

[reynoldston]

The first thing that I do is find and print the wiring diagram, I then enlarge it in portions on my printer and put the sections back together.
The flow of electricity is like water in plumbing. You need to find the initial source and trace each circuit from there. No wiring diagram is totally complete, so I add in the missing items on my enlarged diagram, for example, the battery, the specific engine electrical adapter and the charging system output connection to the terminal on the keyswitch as Scag and other manufacturers don't show this for some reason. As one becomes familiar with Scag electrical systems, the function of the electronic control module becomes more evident and I make notes to these functions on the wiring diagrams.
While in the US Army, I taught aircraft maintenance as part of " additional duties assigned", I learned very soon that I had to start with basic math/algebra before going into basic electricity. And I had to drop algebra from the course title and just call it Basic Math as the word algebra was intimidating to some students. I would work in basic algebra during the course and then tell the students that they now have already been using basic algebra. Then go into basic electricity and get out the aircraft wiring diagrams, and take them out to the actual aircraft to see the actual wiring. Their confidence and skill levels would improve which was gratifying to me as an instructor.
Then we got into hydraulics and with already having math and electricity behind them, hydraulics came easily to most of them.

That I find that is the reason they have problems with electricity. Water only go's one way and electric has to go back to where it started to work. They are always thinking positive and not negative and without that circle it just doesn't work. Yes other then that it is a lot like water. volts flow, amps. amount of flow. A bad switch may have flow but no amps flow. Myself the electric part of it is my favorite part of working on equipment.

 

[Rivets]

As reynoldston said electrical is fun. It can get very frustrating, but boy does that beer tastes good when you get it figured out. I can't say it too often, HAVE PATIENCE AND NEVER ASSUME ANYTHING. You'll figure it out.

 

[John Ambrosia]

You say you have 12V at the S terminal on the key switch. In step 3 you had 0V at the small terminal on the solenoid, when the key is in the start position. This would indicate that one of your safety switches between the key and solenoid is not closing. What you are going to do now is start at the key switch and trace the wires, checking at each connection to see where the voltage stops. When you find that you have voltage on one side of a switch, but not on the other side, jump this switch and try starting. This way you will diagnose the bad component or connection. Remember what I said in the troubleshooting procedure, DON'T ASSUME ANYTHING. Get a buddy to help you and have patience, electrical troubleshooting can get very frustrating, plus double check everything. It may take ten minutes or five hours. Post back if you need more help.

The green solenoid wire goes from the key switch to a relay. I have been told these relays can fail and may be responsible for my failure to crank problem. Can you advise how to check the relay? I had tested the safety switches for continuity earlier but not for voltage and they were ok. What do you think?

 

[Rivets]

I don't know your electrical expertise, but you need to be very careful, as you can burn up a relay quickly if you touch the wrong terminal. I shouldn't do this, assume, but I think the relay you are talking about is like the center compression relay in this attached picture. A relay is just like a solenoid, one electrical circuit controlling another. In this case the circuit between terminals 30 and 87, is controlled by the circuit between terminals 85 and 86. If you hook a continuity meter (your VOM set on Ohms) between 30 and 87, and apply 12V across terminals 85 and 86, the switch should close and you should see continuity or 0 Ohms on the meter, indicating the relay is good. If you don't have is type of relay, don't try this test. BE CAREFUL AND DON'T ATTEMPT IF YOU DON'T FEEL CONFIDENT IN DOING THIS. If you do test the relay and it is good, then you must continue to check voltage across each of the safety switches as I posted before. I know you said you checked them for continuity, but I always check to see that voltage is going through. NEVER ASSUME ANYTHING. If everything tests good, I would take the unit to your Scag dealer and ask him if he would swap out the module, as this is one electrical part that once it leaves the store 99.99% of the time is nonreturnable.

 

[Fish]

After 3 pages, we recommend you take it to a Scag dealer and beg them to swap out electrical parts!!!

Sorry........ We are just a batch of bad cooks.....

 

[reynoldston]

I have worked for enough dealers to know that they wouldn't swap out any electrical parts. They don't swap out parts in their own shop much less for a customer. What they will do, and a very good chance for free test it for you.