MF Super 90 PTO pressure light

   / MF Super 90 PTO pressure light #1  

dboron

New member
Joined
Jul 7, 2011
Messages
2
Tractor
Massey-Fergusons (several)
I have both an MF85 and Super 90 diesel. Both have a hydraulically actuated PTO clutch. There is a red light on the console that turns on if the hydraulic pressure gets too low. This light is not working on either of my tractors.

The pressure switch is located on a "T" of a hydraulic line that runs from the pump in the transmission housing up to the Power Steering unit before returning to the PTO clutch area. A single wire runs from this pressure switch to the light on the console, which also has a lead from the battery source.

I have not been able to come up with a wiring diagram or description of how this pressure switch is supposed to work. Since there is only one wire, I assume that the switch represents the "ground" on the electrical circuit, but if that is the case, why wouldn't the light glow when the engine is off?

Can anyone explain to me how this switch and circuit is supposed to work?

If the switch is bad, can anyone tell me where I can locate a replacement?

Thanks,
Don
 

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