BobCat T190 aux hydraulic switching problem

Son has a T190 with a high flow (26 gmp) aux hydraulic fittings on the boom. He just took the bucket off and put on a clam shell type bucket. Apparently the clam will open, but not close. I asked him how it worked and he said it is solenoid that switches the supply and return hoses to make the bucket open and close ??

I plan to go over on sunday and help him trouble shoot. I have no clue how this works as I have not operated the tractor. He said something about having several buttons (el switches ) ? Is this just a solenoid that moves a piston to switch the two ports or ? Any common problems I should know about ? Easiest way to trouble shoot ? Normally an electrical problem or hydraulic spool prob ?

well, we had the dirt bucket back on for 2 weeks.. Took it off yesterday and put the clam shell bucket with aux hydraulics back on....... Still no clam or grapple operation. Does not seem to even try to move the cylinders. Boy has a aux hyd electric button on the right control handle. He says you push that and then move the handle and it is suppose to work the grapple. We lifted the cab and looked at the electrical plugs ( about 40 wires) and both connectors are plugged in. There are two electric solenoids on the top of the hydraulic valve body that I assume are the aux spool. We pulled the solenoid magnet off the top and he pushed the electric button on control lever and we put a nail inside the solenoid and felt no "magnet"..... I don't see any test ports.. Should we be looking at electrical signal to the solenoids, power to the switch (wire colors?) , or pulling the spools.. It does not appear to have anything... not erratic, nothing... IDEAS ??

steve(ill) said:

Boy has a aux hyd electric button on the right control handle. He says you push that and then move the handle and it is suppose to work the grapple.

Click to expand...

Just to confirm the way a Bobcat works, you push the button on the left console to activate the auxiliary circuit. Once you've done that, there's a thumb switch on the right control lever, move it to the left and to the right from center to operate the auxiliary hydraulics.

Yes, the two solenoids at the top of the main hydraulic control valve controls the auxiliary circuit. If you have a fault with the wiring harness or a fault with one of the coils the ECU should see that and give you an alert, do you ever hear three beeps from the alarm?

If not, likely a mechanical problem with the auxiliary circuit. You stated that the circuit will open the clam bucket, but not close it. Remove the solenoid valves and swap them, see if the problem is now opposite.

thanks willie... I might get back to it mid week when it starts raining outside... Bucket did open ONCE when he was playing with it 3 weeks ago.. Now nothing, no open, no close........ I hear no alarm.. that's the first thing I asked if he saw an alarm. I guess we need to look inside the valve body.. I think he had the solenoids off last summer when we were looking at another problem and didn't know what we were doing. Will check if the rods inside the solenoids will slide up and down......... then look at the hydraulic spools I guess ?? Wish there was a better test to narrow it down.......... thanks

Well, yes, we do need more input. So far what you've described isn't typical with Bobcat machines. What I mean is, if there's a problem in the electrical system that controls the auxiliary hydraulic system, the ECU will see that and sound three beeps from the alarm indicating an active fault code. Aside from that, you could have a faulty proportional switch on the right control lever. As for the control valve, it's rare for them to have a mechanical problem like you describe, would operate in one direction but not the other, then suddenly neither direction works.

Something weird going on with that machine, I'd need a lot more info to have any clue of where to go checking it out.

should I check voltage at the switch on the left lever, or right ? Maybe pull the solenoid wires off and check if I get a signal at that point ? Is it possible to have an electrical problem without getting the ECU code- beep ?
------- it did work once for a second when he was "pushing buttons" 3 weeks ago.... then nothing since then. That's why I was thinking electrical......... I guess it would be a better chance that the control button or toggle button has a problem than BOTH solenoids or BOTH spools ???

Question 1: I don't know if there's a way to test the proportional switch on the right drive lever. There may be a way, but I have no knowledge of that.

Question 2: Wouldn't help to test voltage to the aux solenoids. First of all, you'd have to probe the wires because if you disconnect them to test the ECU would see a broken circuit and lock it out. Second, that's not an analog voltage signal that the ECU sends to the solenoid coils, it's Pulse Width Modulation, a volt meter wouldn't be able to measure that, you'd have to have an oscilloscope.

Third question: Yes, but rare. The ECU see pretty much everything that's an electrical fault. In rare cases something in the wiring will happen and the ECU can't see it and cause funky things to happen. For example, I once worked on an S205 that the ECU would lock out everything including starting engine. I like to never found it, but turned out to be the power wire on the harness that runs down the left loader arm to the 7 pin connector was pinched and shorting out. Although that wire was not directly connected to the ECU, it noticed a problem in the wiring, it just didn't know where it was, so to "self preserve" itself and the system it locked everything out.

One question, when you turn on the ignition to start the machine, do you hear a single long beep from the alarm? If not, the alarm may have gone kaput. It's important that that alarm work to indicate an active fault code in the ECU.

You could ohm test the coils for the aux, should read somewhere around 3.3 ohm. Aside from that, I'm at a loss as to where to go. Be sure and check your harness good, all connectors, and make sure the black wires at the aux coils are making a good frame ground. Oh, and do not attempt to pop test the coils for the aux valves with 12V, those are 9V PWM coils, 12V will cause them to loose their smoke.

thanks for the advice willie ............. we were just talking about jumping a wire to the coils to test them... good thing to get your info first..... will check ground wires and ohm test things for continuity... no 12 v jumpers.

took the wires off of one solenoid tonight and got the beep- alarm. Measured the ohms on each coil and was about 5 ohms... probably variation in the meters. Layed coil off to the side and put a screwdriver inside the coil. Energized with the control button and it would pull the screwdriver so we decided the electrical system was working.
Took one hydraulic spool out and they are spring loaded. Spool seem to drag and had to be pushed out kind of hard. Oil was old last year- drained and installed new ... thinking now is that contamination on pilot spool and they are "stuck" so magnet and springs can not stroke them. Pulled both hydraulic piston / springs and polished and flushed out the oil cavity. Reinstalled and all works OK...................... Thanks Willie for getting us on the right track. We are electrically and mechanically inclined, but needed some guidance on how/ where to start checking.

This machine was new to us 10 months ago. Had trouble with machine dieing after several minutes of operations... Came to this site and Willie and others talked about alarm panel / codes .......checked and, ended up changing out the speed pickup on back end of motor, by the oil filter, it was bad.............. Lots of good help here !

Good to hear you got it working steve. Sounds like there's other things going on since you found that sticky spool, just no way for me to say for certain, only saying that could be a symptom of other issues. Pull the hydraulic filter after some hours, maybe 50, drain the oil in a clean pan and look for metallic debris, then pour some solvent in the filter, diesel fuel, varsol, agitate and pour it out again looking for debris. Change it again in another 50 hours doing the same. Also, check the case drain filters for the drive motors.

I got a problem with my bobcat t 190. Its got a grappel bucket when i open it and leave it open it starts to close by itself what could that be

Mr willie59,
I'm new to the forum. I am having the same problem on a s185
The aux isn't working. The light comes on, I can pull the right hand controller front button and bucket will open but the thumb rocker isn't responding in anyway. I switched the soloinod from one another and pull the trigger and bucket closes but still nothing from rocker switch. I replaced the entire right hand controller with a new Orem one, changed all pins correctly and same issue, no response from thumb rocker.

Smokey03 did you ever solve your issue? I am having the same problem with my 773G.

Pineyman or Smoky03, ever come to conclusion on the issue you were both having. My 773G is doing the exact same thing and I am at a loss on how to continue from here.

Thanks