# Case IH 75C



## 2fatboy (Jan 28, 2013)

Will not go into 4wd. All fuses are good, checked relay and it’s good. When I put my foot on the brakes I can feel the relay working but the green light doesn’t come on. Any ideas of what to check next? The user manual is just that. No help. 


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## LouNY (Dec 15, 2016)

Are you sure it's not in 4wd.
Many of the larger CIH tractors are always in 4wd until the tractor is started and running,
the switch for 2 or 4 actual energizes the solenoid allowing hydraulic fluid to deactivate the clutch pak against it's spring.
I see you have checked your fuses.
Even hearing a relay activate it can still be bad. 
Is there power to the relay base to go out to the solenoid.
Likely pin 30 of the relay socket.


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## 2fatboy (Jan 28, 2013)

I will check the pin 30 tomorrow. 
It’s not in 4wd for sure. I did swap the relay out just to be sure and it’s doing the same thing. 


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## 2fatboy (Jan 28, 2013)

Power is on 30 when brakes are applied. Power is on 87a constant. 
Changed relays again and still no difference. 

When I use the test light to middle pin in the block, the light in the dashboard will turn on and off with the switch. I’m not familiar with this relay so I’m not sure I’m even on the right track. 

Seems to me that the relay is working so where do I go next?














































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## LouNY (Dec 15, 2016)

That looks like an ISO micro relay but it is labeled like a mini relay,
do you have a photo identifying which pin is what?
The normal ISO Micro is 1,4, 2 on the 3 terminal side and 5 and 3 for the 2 terminal row.
#1 and #2 are the relay coil which are #85 and #86 on your relay diagram,
then #4 would be Your #30 with #5 and #3 to #87and #87A


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## 2fatboy (Jan 28, 2013)

I’ve been working on it this morning, it’s now in 4wd the light on the dashboard never lights up no matter where I put the switch and now I can’t get it out of 4wd. I have no idea what is going on. 


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## 2fatboy (Jan 28, 2013)

I have no type of wiring diagram. Can’t find anything online for it. 


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## LouNY (Dec 15, 2016)

That seems to be a strange one.
I see a 4wd switch and it's common to have the brakes bring in the 4wd, but usually the lamp lights up.
Off the top of my head you should have a solenoid, often located in the area of the front drive clutch pac,
*4WD ELECTROHYDRAULIC ENGAGEMENT - IDLER CASE AND SOLENOID VALVE *
Case IH FARMALL 75C - TRACTOR(09/11 - ) Parts

*4WD ELECTROHYDRAULIC ENGAGEMENT - 4WD TRANSMISSION SHAFT*
Case IH FARMALL 75C - TRACTOR(09/11 - ) Parts

Looking at the pictures in the parts breakdowns it looks more like the solenoid activates a mechanical shift for 4wd,
once engaged even when the off command has been given gear bind could make it stay engaged for a while.

When you activate your 4wd switch do you hear the solenoid or any relays pick up.
You may need to disconnect the solenoid wiring and look for voltage on the connector or have someone activating it while you
feel and listen for it with the key on and tractor off.

Normally when the switch is turned on the solenoid should be powered and the solenoid activated and it should stay activated untill switched off.
The auto 4wd brake activation should work when the tractor is in 2wd usually at certain higher speeds appling the brakes will activate the 4wd so 
you get front wheel braking through the 4wd system.

You may need to breakdown and buy a manual for it, some of the online ones are decent and not badly priced but it is a hit and miss guessing game.

The larger older CIH's (7100's and 7200's) the front drive is engaged by a power loss to the solenoid, when the tractor is started and the switch is set to turn off the 4wd the solenoid activates to disengage the front drives then when both brakes are applied at high speeds it will automaticly engage the front drive by switching off the solenoid

Good luck.


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## LouNY (Dec 15, 2016)

I don't know what this will get you;




or this one, the first pages look good'
CASE IH FARMALL 75C Tractor Service Repair Manual


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