overide the electric hydraulic

01gentdc

Well-known Member
don't know if you guys can help or not ,, but here goes my 750 massey has electric header hydraulic control ,.. and I kinda wisht it didn't,,.. perhaps a relay or a resister is bad ,, have no idea where to look ,.. or how to find the problem and or diagnose ,.,. the electric tach and air fan and dash lites all go out when the hydro guits working ,,. does anyone know , IF ,,there anyway to override the circuit and manually trigger the pump to raise and lower
 
Sounds like your "cab relay" and/or wiring associated with it need some attention. IIRC, an oil pressure sender and associated circuitry is involved, as well. If you post back with a serial #, I MAY be able to come up with a wiring diagram for you, but start with the "cab relay".


"anyway to override the circuit and manually trigger the pump to raise and lower "

The pump isn't the issue, the hydraulic valve has several solenoids that need power to function.
 
(quoted from post at 23:10:08 12/19/15) Sounds like your "cab relay" and/or wiring associated with it need some attention. IIRC, an oil pressure sender and associated circuitry is involved, as well. If you post back with a serial #, I MAY be able to come up with a wiring diagram for you, but start with the "cab relay".


"anyway to override the circuit and manually trigger the pump to raise and lower "

The pump isn't the issue, the hydraulic valve has several solenoids that need power to function.

If the oil pressure sender is the issue, then your electric system should restart if you push on the "safety ovveride switch" on the cab roof.
 
wow ,thanx bob for the quik reply ,,. I do have a parts book and op manual , my 750 was one of the very last gray cab 750s built ,.when it comes to electronix , I am not as good as most folx ,,. ,. more than likely it is one or both of those solenoids relays under the rite panel,,.who knows it mite be a common automotive relay ,,. not lookin forward to paying agcos price for something that mite not be broke ,.. usually ,, at 1st startup,.everything worx..tach lites up ,I hear a relay clik regardless of whether I have electric or not , , then after a hour or so,.i loose all power to the tach , hydraulix and my cab fan , most times if I shut off the motor for a minute all comes back on and worx fine ,. I suspected my ignition switch ,so I got a new one ,,. and all was fine for a month or two,,. I have found that swappin ignition switches would restore electric every time ,,. but not lately,.the problem is getting worse . when roading the electronix usually loose power after a couple miles , not good when ya get to the field and you want to kik it in gear and start combining . and the durn head is up with a 4 hour erection ,.. LOl ,. if I wanted to road the combine home ,,.it would be nice to be able to overide a switch and make it lift ... but from what I am learning it really is easier start replacing solenoids and relays ,. than to crosswire a solenoid switch and risk messing up more delicate equipment ,.
 
Had trouble like that on my 4690 Case tractor. Cab functions would work and then quit until it decided on it's own to start again. Cab solenoid from Case-IH was near $200, but went to NAPA and got one for $32. All good to go now. Take the old one to NAPA and find the old guy that will find a replacement. I'll see if I still have the box with the number on it....probably would work for you.
 
So you never tried to push this button while your combine was down? This would tell you if the problem is in all the bells and whistles that control your combine or in the cab wiring: Relay ground, relay power (so key switch; fuse box, etc..)

A8665ZZZC.JPG
 
certainly do apprexiate the help guys ,, my machine has about 3700 hours on the engine . P owner removed murphy switch ,. , so the override switch is probably disabled ??? it makes no difference when I push the switch ,,. called the dealer /mechanic this am ,, he said this problem occurs once or so in the life of a machine ,, more than likely the oil sending units ,,. told me to to jump 2 wires from both sensors together and see if that lites up the electrix ..,,if that makes no difference then it probably is one or both switches,,. he also said to make sure the oil is full , since the murphy switch is hookt to the oil switch and its only defense is to shut down electric ...
 
Actually, if the oil sending unit was wrong, you would have override this error with the button. Unless both are bads, which is hard to believe.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top