720 pony wiring

Austin White

New User
working on rewiring a 720 diesel pony start. I'm puzzled by the red dash light. One book i have says it's a generator charge light and another says it's an oil pressure light. Which is it? I can't find an electric oil pressure sensor. It seems redundant since the tractor has both an amp and oil gauge.
Thanks
 
I think how it works is that blackdash models it was an oil light for indicating that the pony have oil pressure. For the models prior, the red light was to let you know that the key switch was still on. I might be wrong but somebody hopefully will chime in with more.
 
On the 70 D this lamp was on whenever the cranking ignition was switched on.

I believe the later 720's & 730's the lamp was on only when the cranking engine ignition switch is on but the cranking engine is not running! Once the cranking engine has oil pressure a pressure switch turns the lamp off. After the diesel is running and you turn off the fuel to the cranking engine letting it run out of gas & stop, the lamp comes back on to remind you to turn the ignition off. It's so easy to ignore and forget that lamp on the 70 that I've made it a habit to just NOT drive it until the cranking engine has stopped.
 
the red light when on is to tell you the switch is in on postion. when cranking the pony motor and oil presure builds the light goes out, and when big engine is running pony motor is to be turned off. IF the switch is left on for long period of time you can burn out the pony coils for ignition.
 
And it doesn't really take that long. You only let them burn up once. After you buy new coils once, you will watch a lot closer.
 

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