testing solenoid on starter motor

[mitch becton]

by application your should have a denso gear reduction style starter the solenoid contacts are the number one failure on these units you should see a triangle kinda plate with 3 bolts takes this off there is a spring loaded plunger that will come out you will see 2 copper contacts inspect and possibly post pictures while in housing if they fail starter will do nothing this is the first electrical contact for cranking this style unit

 

[tonybalnaves]

thanks all for your input much appreciated have solved the problem... it was a broken cable from ignition switch to the solenoid {or it is fused ..but I traced it and can find no fuse } tractor is now running again ..thanks again to everyone

 

[Silvic]

Well I was watching this thread as I am having a similar but not the same issue with a Denso starter. When the starter switch is pushed the engine turns 1 or 2 rotations (1/4 second) then goes silent for 5 seconds then repeats. When I jumped the solenoid directly to 12 v same thing except maybe a little longer rotation by a little. Not the battery and the manufacturer has swapped out all the harnesses. Seems no one want to consider the starter as the suspect. Warrantee thus have to do their plan.

 

[Keith_B]

Well I was watching this thread as I am having a similar but not the same issue with a Denso starter. When the starter switch is pushed the engine turns 1 or 2 rotations (1/4 second) then goes silent for 5 seconds then repeats. When I jumped the solenoid directly to 12 v same thing except maybe a little longer rotation by a little. Not the battery and the manufacturer has swapped out all the harnesses. Seems no one want to consider the starter as the suspect. Warrantee thus have to do their plan.

Sounds like it coyld be starter brushes.

 

[whiterose]

The solenoid is just a big current electrical switch. So a smallish current can make the solenoid make contact and pass a very high current to the starter motor. This gets around having to have a massive switch instead of the wee one on the start/ignition cranking switch.
Usually the battery negative is directly grounded to the chassis somewhere near the battery, then a heavy cable/wire is taken to the solenoid. All that is needed then is to get that solenoid to switch and the starter circuit is energised- the motor turns - the engine starts. A relay, contactor, start solenoid are all the same family. They have a low current circuit switch a high current circuit.

Remove the wire that feeds the solenoid and see if there is continuity with an ohmmeter. It will be a very small resistance if working. One terminal of the meter to ground/chassis, body of solenoid/motor and the other terminal to the hot contact of the solenoid.
If you do get a low reading connect a wire from the battery positive to the hot terminal on the solenoid to see if it clunks on off. You will need a good connection to the body of the solenoid/motor or chassis. If the battery is still connected on the tractor this will do fine. I would remove the battery positive while you test.
Be careful to remove the wire that goes to the starter as you don't want the tractor moving off on you. Or put in neutral- just think it out.

 

[BigRol]

Thats an oldie skyhook, pos ground

 

[skyhook]

Ya, I just noticed it, I wonder if they just made a mistake with the signs on the battery.

 

[BigRol]

Could be, but I still do some work on pos ground units, mostly old farm tractors.

 

[Trials]

Ya, I just noticed it, I wonder if they just made a mistake with the signs on the battery.

Do you mean like the positive terminal is marked as negative and the negative is marked as positive ?

The two posts also differ in size! Pretty hard to get them mixed up if you are only test connecting them one at a time.

 

[Trials]

Ya, I just noticed it, I wonder if they just made a mistake with the signs on the battery.

oops, that double posted.
Hi