7400 hard start

[sam un ont]

I am working on a neighbours 7400 that has been neglected from day one. One problem is no power to the starter Fromm the key. I have checked out the solenoid by the alternator and I壇 will crank the engine when voltage is applied
Crawled under to check the neutral switch and it checks out but no voltage is there when the key in in the start position
Tractor can be started by applying voltage to the small terminal on the starter
Under the tractor at the neutral switch there is the plug with 2 wires and there is one small red one just laying there
Does anyone have a diagram for the start circuit and secondly does this tractor have glow plugs

Thank you very much




Sam

 

[jd110]

There is a grid heater in the intake for cold starting. It is activated by turning key on and then pushing in on the key. Have you checked the key switch? does it supply power to the start terminal on the switch? (terminal 6) There should be wire #311 goes from switch to the neutral switch. If power is at terminal #6 at key switch and no power to the neutral switch, the wire is broken somewhere.

 

[sam un ont]

Thank you so much for your input. The key switch checks out fine and power is leaving but nothing at the neutral switch. My query is does the power from the switch go directly to the neutral switch, or does it go first to the pto switch and then to the neutral switch? One final query does the start relay on the engine get its activating power from the pop switch or the neutral.
What I really need is the path the power takes from the key to the start relay up by the alternator


Thank you once again

Sam

 

[jd110]

The pto switch is not in the starting circuit at all. The power goes from key switch to the neutral switch by wire #311. It leaves the neutral switch and goes directly to the starter relay by wire #301. If the pto switch is left on, the tractor should still start, but the pto will not run until the switch is turned off and then back on.

 

[sam un ont]

Thanks for the info. I was under the impression that it was tied in with the pto switch as I had found that in a few posts.what also lead me to think that also was the fact that I had no continuity from the neutral switch to the key
Or from the neutral switch to the relay but what you say makes sense. I will just keep looking for a break in both wires.unfortunately I do not have even an operators manual and John Deere dealer is little help
Sam