Electrical problem can someone explain this circuit

[timbatrader]

I have a Chinese pivot steer loader Mountain Raise MR926S it sometimes refuses to start if I flick the key on off a dozen times or so the relay clicks in and it goes it seems to not be the starter solenoid but another relay in the system I am trying to work out the reason for or function of a few items in the circuit
the electricity lock, the electromagnetic switch, the power switch of start in the attached circuit diagram

 

[mrmikey]

These are only guesses but here goes.
The electromagnetic switch is the fuel solenoid which has two windings, the pull in and hold, that's probably what you hear clicking when it won't turn over. The pull in winding gets it's power from the starter solenoid circuit as it's only used to initially pull the plunger in so it only needs to have power long enough to pull in the plunger, this happens when the starter solenoid is energized ......and supposed to be engaged. It sounds as if your starter solenoid is sometimes not working.
The power switch of start is the starter switch, it engages the starter motor and energizes the pull in windings at the same time as long as the starter is engaged and appears to control the glow plugs?
The hold winding gets its power from the electricity lock which appears to be a master switch.....Maybe.
That is one wild schematic for sure LOL..........MIke

 

[Ken]

Might be the same designer for John Deer's display panel. ignition sw. to F7
then at display panel divides into 2 power supply voltages to pull the start circuit and the second to the fuel circuit. should any cause the safety check fail engine will not start. . more important to have flashing lights than a tractor to use. Ie error that left turn signal filament missing. error, error, displayed. have to fix before using the tractor. Just a 1/2 inch jumper fixes the fault and can use the tractor. a failure of 10 cent diode and replacement is 1600.00 bucks +125 per hour for each of 2 mechanics to replace. 8 hours
experience is a good teacher. the old remain running while the new stays in the shop. Look at the value of the 10-year-old tractor is more than new.
Just my opinion. ken

 

[workinonit]

The electromagnetic switch is your start relay. The PSS is your key switch or starter switch. When the switch is turned power is provided to the EMS and is sealed in through the relay or EMS contact which sends power to the starter. Any of the 3 components could be your issue. You would need to see if you are getting power to the starter during the times the clicking is happening and it doesn't start.

 

[timbatrader]

Thanks for the replies its not a relay for a fuel pump as it came from the factory with a mechanical pump I have since wired in an electric pump taken power from the fus

e box through a new fuse from sause that only has power when the key is on
Note when it has the problem the fuel pump doesn't operate if i keep flicking the key switch the radio speakers click at some stage something latch's and the fuel pump kicks in once the fuel pump starts clicking I know the starter will work. A couple of photos attached two relays

on the machine and the new one that came with the machine in the box of spares