Bobcat 753 boom/bucket interlock

[RODBUILDER]

I have a later model 753 that has the bucket release switch under the "ignition" key. It starts great and motivates with no problems, BUT the foot controls don't release all the time. When this happens you can move the foot peddles but all it does is make the pump growl.

When it's not working right............

1. When you hit the electric switch under the key you can hear the solenoid valve clunk.
2. The foot peddles DO move, but if the problem is there all you get is a growl from the pump - like the hydraulic fluid isn't being allowed to flow through the lines, and there's no boom or bucket tilt.
3. Because of where the Bobcat geniuses put the computer you can't see the lights on it, so I don't know if they're on or not!!
4. But when it decides to work it operates great!!

Why they have to put stupid computers on this stuff is beyond me!!!

Thanks for any experienced help on this.

 

[willie59]

That's a 753 F Series machine.

You're having a problem with the lift/tilt lock system, part of the BICS (Bobcat Integrated Control System). Yes, it's sort of a computer, but more of a safety device to help keep stupid people from killing themselves with moving loader arms just 3 feet in front of them, and the world has no shortage of stupid people.

Yes, on the C and F series machines, the BICS controller is in an awkward spot to view, mounted on the rear panel to the right of the seat, but when this problem comes up you need to try and view the LED lights on the BICS controller and see if the LED for Lift/Tilt lock is flashing a code.

BTW, the clunk you're hearing when you push the button to operate the machine is the parking brake solenoid releasing the brake, the lift/tilt lock is a different part of the system.

 

[RODBUILDER]

That's a 753 F Series machine.

You're having a problem with the lift/tilt lock system, part of the BICS (Bobcat Integrated Control System). Yes, it's sort of a computer, but more of a safety device to help keep stupid people from killing themselves with moving loader arms just 3 feet in front of them, and the world has no shortage of stupid people.

Yes, on the C and F series machines, the BICS controller is in an awkward spot to view, mounted on the rear panel to the right of the seat, but when this problem comes up you need to try and view the LED lights on the BICS controller and see if the LED for Lift/Tilt lock is flashing a code.

BTW, the clunk you're hearing when you push the button to operate the machine is the parking brake solenoid releasing the brake, the lift/tilt lock is a different part of the system.

Thanks. I'll get back to you if we can't figure it out, or need some code ciphering. I saw a note on the net somewhere that pointed out the seat interlock, so we're going to eliminate that possibility by bypassing the seat interlock tomorrow and go from there. Someone else made mention of a low hydraulic fluid condition so I'll check that out too.

But thanks and I'll get back to you.

And a big 10-4 on the stupid people!!!

Phil in Illinois

 

[willie59]

The BICS controller on the C and F series machines have very early On Board Diagnostics, much like OBDI in the automotive industry in the '80's. If there's a fault it will flash on the LED lights on the BICS controller. But even then, it's not very specific, pretty much tells you there's a problem with that part of the system. When Bobcat progressed to the G Series machines the BICS diagnostics got way better, much like OBDII.

Yes, the seat switch is problematic on C and F machines, maybe the reason Bobcat did away with them on the G Series, that and the BICS system really didn't need it by that time. As for by-passing the seat switch, not an easy thing to do as it's a Hall Effect switch, not a system you can simply "jump some wires" and go around it. Bobcat does offer a kit to do away with the seat switch on C and F machines, don't recall the part number though.

 

[crewchief888]

as willie mentioned, you need to check the idiot lights on the BICS controller before you start bypassing anything.
those lights will give you an indication as to what part of the system is at fault.

several things have to happen before the brake and hyd will unlock.

seat sensor (if still equipped) meaning the operator is in the seat
seat bar has to be down, again to insure the operator is in the seat
the loud clunk you hear is the brake solenoid pulling the brake up.


:drinkup

 

[RODBUILDER]

The BICS controller on the C and F series machines have very early On Board Diagnostics, much like OBDI in the automotive industry in the '80's. If there's a fault it will flash on the LED lights on the BICS controller. But even then, it's not very specific, pretty much tells you there's a problem with that part of the system. When Bobcat progressed to the G Series machines the BICS diagnostics got way better, much like OBDII.

Yes, the seat switch is problematic on C and F machines, maybe the reason Bobcat did away with them on the G Series, that and the BICS system really didn't need it by that time. As for by-passing the seat switch, not an easy thing to do as it's a Hall Effect switch, not a system you can simply "jump some wires" and go around it. Bobcat does offer a kit to do away with the seat switch on C and F machines, don't recall the part number though.

willie59

When the switch decides to take a crap, which solenoid does it control and where is it at?

If it's the same one we hear when we press that switch under the "ignition" key I would thing it will be easy to find.

Thanks man

 

[crewchief888]

willie59

When the switch decides to take a crap, which solenoid does it control and where is it at?

If it's the same one we hear when we press that switch under the "ignition" key I would thing it will be easy to find.

Thanks man

none of the switches directly control anything. they are sending a signal to the bics controller


:drinkup

 

[willie59]

none of the switches directly control anything. they are sending a signal to the bics controller

Exactly. So if you push the operate loader button and it releases the parking brake, that means the push button switch is operating proper, it's sending a signal to the BICS controller, and the controller reacts by releasing parking brake. Given this, if the lift/tilt won't unlock, you likely have a problem with the BICS controller controlling that circuit or something beyond the BICS controller, wiring, solenoid, etc.

 

[RODBUILDER]

Willie - where is that solenoid that the seat switch controls?

 

[willie59]

Willie - where is that solenoid that the seat switch controls?

The seat switch "does not" control any solenoid, it only sends an input to the BICS controller, same with the seat bar switch. You really need to check the lights on the BICS controller. With engine running, seat bar down, and sitting in the seat the LED for lift/tilt lock on the BICS controller should be lit up. If it's not lit up the BICS controller will not unlock the lift/tilt lock on the main control valve. If that LED is flashing, it's flashing a code.

 

[RODBUILDER]

The seat switch "does not" control any solenoid, it only sends an input to the BICS controller, same with the seat bar switch. You really need to check the lights on the BICS controller. With engine running, seat bar down, and sitting in the seat the LED for lift/tilt lock on the BICS controller should be lit up. If it's not lit up the BICS controller will not unlock the lift/tilt lock on the main control valve. If that LED is flashing, it's flashing a code.

Whatever - but where is the lift/tilt unlock solenoid? THAT is what I want to get to! If I run a hot wire to that there's no way the computer can interfere with it again.

 

[willie59]

Whatever - but where is the lift/tilt unlock solenoid? THAT is what I want to get to! If I run a hot wire to that there's no way the computer can interfere with it again.

I really do hope you understand where I'm coming from with this comment, and I have a record on this forum of going to great lengths to help folks here with their problems, but with what you just asked, and given our law happy society where McDonalds can get sued because coffee is actually hot (who knew?), there is no way I'm going to make a post on a public forum of how to work around and disable an OEM safety device. The legal implications for me go far beyond the problem you are having since things on the internet live forever.

But I will say this, if you get a maintenance/service manual for you machine it will give you the answer you're looking for.

 

[crewchief888]

I really do hope you understand where I'm coming from with this comment, and I have a record on this forum of going to great lengths to help folks here with their problems, but with what you just asked, and given our law happy society where McDonalds can get sued because coffee is actually hot (who knew?), there is no way I'm going to make a post on a public forum of how to work around and disable an OEM safety device. The legal implications for me go far beyond the problem you are having since things on the internet live forever.

same for me....

i could tell you,
but i wont.... for your own safety.


:drinkup

 

[RODBUILDER]

Willie -

For the manual - the S/N on this 753 is 515818547

After we put a hot wire on, what I think is the tilt/boom solenoid, located at the left/front corner of the pump house, under the seat, the machine SEEMED to operate normally. But after we let it sit outside overnight, the problem re-sufaced all over again!

Then, I let it sit there idling for maybe 4 or 5 minutes and tried it again and BINGO - the damn thing operates like a new machine!!!

When I bought the machine last week we discovered that someone had apparently left the cap off of the Hydraulic reservoir and it got some rain in it, because the hyd. oil was milky, so we flushed it out and installed new hydraulic fluid.

I'm wondering if , maybe the spool valve inside the boom/tilt control valve might have a ring of corrosion around it (from the water) and warming it up loosens it enough so that it works? But having owned 20 or 30 skid loaders in the past 15 years or so, this is the damnedest thing I've ever come across!!

 

[RODBUILDER]

Exactly. So if you push the operate loader button and it releases the parking brake, that means the push button switch is operating proper, it's sending a signal to the BICS controller, and the controller reacts by releasing parking brake. Given this, if the lift/tilt won't unlock, you likely have a problem with the BICS controller controlling that circuit or something beyond the BICS controller, wiring, solenoid, etc.

Yeah - but why isn't the bucket control releasing until the machine warms up for a bit?

 

[RODBUILDER]

I really do hope you understand where I'm coming from with this comment, and I have a record on this forum of going to great lengths to help folks here with their problems, but with what you just asked, and given our law happy society where McDonalds can get sued because coffee is actually hot (who knew?), there is no way I'm going to make a post on a public forum of how to work around and disable an OEM safety device. The legal implications for me go far beyond the problem you are having since things on the internet live forever.

But I will say this, if you get a maintenance/service manual for you machine it will give you the answer you're looking for.

No I really don't. If people don't have the frikkin' brains to shut off a skid loader before they get out of it, I look at it this way: When the dumb ass dies he won't be able to reproduce anymore and bring equally stupid kids into the world!!!

Like I wrote Bobcat's CEO last night - if they make these things with ONE safety interlock (on the lap bar) that's all that's needed to keep someone from getting killed on one of these things AND keep them out of court. If someone (like ME!) is going to disable anything he's going to disable everything. I'm a firm believer in the mantra "KISS" - Keep It Simple Stupid!!! Why does a skid loader need more than one safety interlock on it?

Going a bit farther with this, it's like our car seat belts. If the insurance companies want to mandate us wearing seat belts, then put a clause in our insurance policies that voids it, if it's shown that we weren't wearing one when we get in a wreck.

But complicating a simple skid loader by putting computers and other garbage in them is just plain stupid and I told that to Bobcat's CEO. The ONLY reason they do this is to put money in their pockets and make us (or TRY to make us) take the machine to one of their dealers to get it fixed...............but it's not working out for them very well - is it? They're gonna have to put "DR." in front of their names before this white boy hands over $100 or more, for anyone to do an hour's labor on anything I own!!!

I agree with Donald - this country has gone to hell in a hand basket.

You REALLY don't think someone is going to sue you because you told them how to disable a solenoid on a bobcat - DO you? Pa-Leese!!!

 

[mikebramel]

I looked at a skid the other day. His "guy" blew a hose and ran it out of oil. Let it run surging till there was no movement. Must have ran it for awhile as the pistons were just about melted. If he had a Bobcat with a charge pressure sensor it would have shut down..... saving him from buying another machine

 

[RODBUILDER]

same for me....

i could tell you,
but i wont.... for your own safety.


:drinkup

...........................and I'm not going to tell you which end of a fork to hold when you eat, because you might stab yourself with it. GET SERIOUS WILL YA?

 

[RODBUILDER]

I looked at a skid the other day. His "guy" blew a hose and ran it out of oil. Let it run surging till there was no movement. Must have ran it for awhile as the pistons were just about melted. If he had a Bobcat with a charge pressure sensor it would have shut down..... saving him from buying another machine

And if he'd gone through it visually and seen the 2 hoses rubbing together he'd gave seen that!! And if he did any maintenance on it, it wouldn't have blown a hose! WOULD it?

So what you're saying is that the manufacturer of any vehicle or piece of equipment should include a warning to it's buyers saying: "Notice:
This machine will NEVER go bad on you. It has 30 interlocks on it along with bells, whistles, computers and all sorts of other crap to protect even the biggest idiot - but doing so has made it impossible to diagnose any problems it might have in the future. If it ever goes bad on you we suggest tossing the piece of crap in the trash and buying another one. But it's highly likely that you'll have the dame problems with it too!!! And whatever you do, don't go to that heavy equipment forum and ask anyone about this because they're all paranoid and think that if they help you someone will sue them!!!"

So posting anything on this forum on how to circumvent any problems on it makes you REALLY paranoid, so you're not gonna do it??? REALLY?

Whatever! I sure hope you need something from someone else some day!

 

[mitch504]

gee opcorn