773 hydraulic gremlins

[shepherd]

Hi, been using this site for info for a few years now, but have never had to post a question till now. My 1997 773 has front hydraulic controls on the right stick, and they have never worked. The lights on the right panel used to function, but no longer do. So, I have a need for a grapple bucket and started to trouble shoot the system. Fuses all good, relays all good. I checked the two switches for operation at the plug, and good there. It seems that the system isn't getting any power, which wire would I check? I pulled the harness, cleaned the plug ends and coated with dielectric grease. Had to solder 2 spots that were rubbed bare. There is a small epoxy coated circuit board behind the left stick, could this be bad, or can it be tested? So after putting it all back together, I still have no front hydraulics. But, now my lift arms and bucket won't operate either. So I obviously opened a can of worms. The lift arm light on the bics is flashing once. I unplugged everything one by one, but can't get it going. I have always had to hit the trac lock override button to drive the machine (another story) but still no lift or bucket function. Any ideas? I'm reaching the end of my patience for tilting the cab up and down while chasing my tail..

 

[Bobcatdan]

One blinking light is "valve output is open." My guess is somethings is unplugged or plugged in wrong. There very well could be unused plugs under there and stuff is wrong. As for the aux not working I wonder if the aux controller went bad.

 

[shepherd]

One blinking light is "valve output is open." My guess is somethings is unplugged or plugged in wrong. There very well could be unused plugs under there and stuff is wrong. As for the aux not working I wonder if the aux controller went bad.

So, going to pull the harness out tomorrow morning and compare it to my wiring diagram. The diagram is a bit hard to trace in PDF, so I guess I'll print it out. Is the controller for the aux hydraulics the computer board I referenced in my post? About 4"x 5" with 2 electrical connections? I wonder if it's just a "replace with good unit" item, or if it can be tested? I get no lights at the upper right button, I wonder if it is getting voltage. Hmm.

 

[TriHonu]

So, going to pull the harness out tomorrow morning and compare it to my wiring diagram. The diagram is a bit hard to trace in PDF, so I guess I'll print it out. Is the controller for the aux hydraulics the computer board I referenced in my post? About 4"x 5" with 2 electrical connections? I wonder if it's just a "replace with good unit" item, or if it can be tested? I get no lights at the upper right button, I wonder if it is getting voltage. Hmm.

If your 773 is an F series with the separate Auxiliary Hydraulics control panel (button with 2 LED's)? If so, the first thing I would check is the PWM fuse. Even if it looks good check it for continuity with a meter.
The PWM fuse protects the Pulse Width Modulator. This is a sealed controller that controls the coils on the Aux Hydraulic solenoid valves.
My Aux Hydraulics just quit one day. I did some basic checks and did not find anything. The Service Manager at my dealer told me what to check and I found it was nothing more than a bad fuse.

 

[Tazza]

If your 773 is an F series with the separate Auxiliary Hydraulics control panel (button with 2 LED's)? If so, the first thing I would check is the PWM fuse. Even if it looks good check it for continuity with a meter.
The PWM fuse protects the Pulse Width Modulator. This is a sealed controller that controls the coils on the Aux Hydraulic solenoid valves.
My Aux Hydraulics just quit one day. I did some basic checks and did not find anything. The Service Manager at my dealer told me what to check and I found it was nothing more than a bad fuse.

Don't over look the contacts on the fuse holder too, they can get corroded and you can't really see it.

 

[shepherd]

Don't over look the contacts on the fuse holder too, they can get corroded and you can't really see it.

So, the lift arms and bucket controls work again! I removed the BICS harness and cleaned all of the plugs really well. Had to use a dental pick to scrape some of the contacts clean, and then put dielectric grease on everything. Resoldered 2 former repairs that looked questionable. The wire has lots of dark oxidation that makes it hard to solder, I found that soaking in a vinegar/ water solution cleans it back to bright copper and I got good solder joints. Removed the ground that connects the cab to the frame and cleaned where it bolts on, and the main battery ground too. Plugged it all together and it works again. So, back to chasing the aux. hydraulics. I ordered 2 new solenoid coils from Bobcat, $27 each. I'm going to stare at the wiring diagram again and see if I can figure what leads power the control board before I cough up $225 for a new board. The tech said, power to the board, the switches, and the coils, that's all there is to it.. With that, what's involved to replace the solenoid coils? Mine have a bad amount of rust on them. I can see what used to be a nut, that is now a blob of rust on top of the rusty coils. Not sure where to start on this one, but I know the coils are bad so it has to be done.

 

[little_fellow]

So, the lift arms and bucket controls work again! I removed the BICS harness and cleaned all of the plugs really well. Had to use a dental pick to scrape some of the contacts clean, and then put dielectric grease on everything. Resoldered 2 former repairs that looked questionable. The wire has lots of dark oxidation that makes it hard to solder, I found that soaking in a vinegar/ water solution cleans it back to bright copper and I got good solder joints. Removed the ground that connects the cab to the frame and cleaned where it bolts on, and the main battery ground too. Plugged it all together and it works again. So, back to chasing the aux. hydraulics. I ordered 2 new solenoid coils from Bobcat, $27 each. I'm going to stare at the wiring diagram again and see if I can figure what leads power the control board before I cough up $225 for a new board. The tech said, power to the board, the switches, and the coils, that's all there is to it.. With that, what's involved to replace the solenoid coils? Mine have a bad amount of rust on them. I can see what used to be a nut, that is now a blob of rust on top of the rusty coils. Not sure where to start on this one, but I know the coils are bad so it has to be done.

How did you make out? Is your aux. hyd. working and if so what was the problem?