763H Secondary Auxillary Hydraulics Problem

[bullrake]

Need some help on this one guys…. I attached my snow plow blade to my 763H when the east coast snow storm rolled in last Saturday and discovered that the hydraulics for the angle cylinders weren't operating properly. I use the secondary auxiliary ports to drive these cylinders and no matter which way I toggle the control switch (left handle, center) the plow blade swings left; pretty useless! I've checked the High Flow circuit with my grapple bucket and that circuit works fine. I have an Ingersol Service manual (one of the most irritating manuals I have ever read) and have tried to diagnose the problem but am having trouble locating components. If I'm reading the schematics properly then I believe the secondary control valve is opened via a relay.... Is anyone familiar with this machine and if so can you point me to where this relay (relays) is hiding? The machine is a 763H, F series, 1999 I believe. Any help is greatly appreciated! Thanks! Paul

 

[mrfixitpaul]

Not sure about there being a relay but have you checked that all the solenoids are in place on the high flow control valve? There are 5 coils ...I think... on that valve, located to the right of the engine, below the high flow pump. Has the plow worked in the past off of those little couplers or is it something you are trying?

 

[bullrake]

Not sure about there being a relay but have you checked that all the solenoids are in place on the high flow control valve? There are 5 coils ...I think... on that valve, located to the right of the engine, below the high flow pump. Has the plow worked in the past off of those little couplers or is it something you are trying?

Yes all five of the solenoids are there and connected, I was going to measure the voltages back there whent the switch was flipped but the connectors are in a nasty spot and there isn't any slack in the harness. When the switch is toggled I cant feel either of the secondary solenoids responding. The circuit worked like a charm last year, the flow is perfect for plow angle; only had to add a cushion valve, no restrictors required. The reason I asked about relays is first I can here one clicking when I toggle the switch, and second, in the service manual there is a schematic for an "attachments control harness" which indicates there are a couple of relays in the circuit.

 

[bobbie-g]

Yes all five of the solenoids are there and connected, I was going to measure the voltages back there whent the switch was flipped but the connectors are in a nasty spot and there isn't any slack in the harness. When the switch is toggled I cant feel either of the secondary solenoids responding. The circuit worked like a charm last year, the flow is perfect for plow angle; only had to add a cushion valve, no restrictors required. The reason I asked about relays is first I can here one clicking when I toggle the switch, and second, in the service manual there is a schematic for an "attachments control harness" which indicates there are a couple of relays in the circuit.

Pardon me for displaying my ignorance: On my 751, the thumb toggle switch will change the direction of the aux hydraulic flow. But the right hand trigger will toggle the flow on in one direction and leave it on. Have to hit the trigger again to toggle them off. And once toggled on, the machine will continue to operate in an almost normal mode. Triggered them on once without knowing it, and couldn't figure out why the snow blade was not acting right. Does not sound like this is you problem, but might be worth hitting the trigger a couple of times. ---RC

 

[bullrake]

Pardon me for displaying my ignorance: On my 751, the thumb toggle switch will change the direction of the aux hydraulic flow. But the right hand trigger will toggle the flow on in one direction and leave it on. Have to hit the trigger again to toggle them off. And once toggled on, the machine will continue to operate in an almost normal mode. Triggered them on once without knowing it, and couldn't figure out why the snow blade was not acting right. Does not sound like this is you problem, but might be worth hitting the trigger a couple of times. ---RC

Thanks bobbie-g. Good suggestion, I hadn't thought about the left handle, auxillary hydraulics working like that. I tried just about every sequence of switches this morning and no luck. My right handle operates the High Flow exactly as you described, toggle sets left/right and the trigger locks in that mode. I believe that my left handle is supposed to control the secondary aux. in the same manner. No matter which switch I toggle on the left control the plow wants to angle left (I believe that this is pressure to the bottom male port on the machine). If anyone is interested I've scanned a couple of pages from my manual and uploaded them to photo bucket, sorry they're not clearest scans. I was trying to minimize file size. The link tothe album is: http://s237.photobucket.com/albums/ff47/bullrake/Bobcat 763H/

 

[bullrake]

Thanks bobbie-g. Good suggestion, I hadn't thought about the left handle, auxillary hydraulics working like that. I tried just about every sequence of switches this morning and no luck. My right handle operates the High Flow exactly as you described, toggle sets left/right and the trigger locks in that mode. I believe that my left handle is supposed to control the secondary aux. in the same manner. No matter which switch I toggle on the left control the plow wants to angle left (I believe that this is pressure to the bottom male port on the machine). If anyone is interested I've scanned a couple of pages from my manual and uploaded them to photo bucket, sorry they're not clearest scans. I was trying to minimize file size. The link tothe album is: http://s237.photobucket.com/albums/ff47/bullrake/Bobcat%20763H/

Well I chased down the wiring from handle controls to solenoids and all voltages were as expected. Measured the resistance of all of the solenoids in the valve and all were within tolerance. Disassembled the select pair of solenoids and found considerable corrosion between the coils and the solenoid body. Removed the solenoid body, it was clean and the springs seemed to be operating properly. Then I moved the valve back and forth several times to insure that it was not stuck. Cleaned everything up and put it all back together again and it worked ….I'm really clueless as to why though, maybe the valve was stuck and I freed it up? Sometimes you just get lucky I guess. Thanks for the suggestions. Paul