I'm having my first real problem with my Cat 248 since I've owned it. The axillary hydraulic circuit is activating on its own for some reason. When I run my 4 way bucket, it opens itself without pressing the button that is supposed to do that function. I can't close the bucket up again until I press the button that is supposed to open it, it kind of cancels whatever signal it's getting to open, then I can close normally. I currently have to disconnect the hoses to the bucket to load material, otherwise the bucket opens whenever it feels like making a mess of things. Because I have to seemingly cancel the "open" circuit by pressing the "open" button, I'm thinking there is a problem in the computer somewhere that controls this function. I would think if there were a short in the wiring, it would not respond to the "open" switch as it does. Any ideas on what this may be and where I should start looking for trouble? Thanks!!
Steve, I would be considering the switches in the pilot stick. This an electric over hydraulic circuit and dirt or moisture would be the culprit I expect. I haven't had cause to look at the actual circuit for this but, when I had the 246, one of the relays for the ECM got some dust in it and played up once. I got the machine going again by simply waggling the wiring where it went into the relays. These are the big relays on the upper right side of the engine bay in the B series. I have the thumb roller in the 248B and haven't had an issue. I think I'll have a look in my manual tonight.
All I have is a service manual and there's no mention of this circuitry in it. I haven't yet had the need for a repair manual, maybe now is the time to look for one.:beatsme
Steve, does your machine have the little yellow rubber buttons on the pilot controls for operation of the 4 in 1 bucket?
Yes it does. They are intact, no cracking or chunking of the rubber. Just over 1500 hours on the machine.
The one we have at the quarry had a similar problem where when you hit a bump the engine would lug down. Hit another bump and it would speed up. It had no Aux. attachments, just the standard bucket. After much troubleshooting they found one of the Aux. buttons to be defective. The mechanism in the button that actually makes the button go "click" when you press it broke and the button was just kinda in limbo. Since there was not an attachment on it the hydraulic strain would lug the motor down. I was not there when they took apart the control so I don't know what is in the joystick. They replaced the button though and it fixed the problem. If there had been an attachment on the machine the button would of activated it when hitting a bump. Just a thought. On edit: I should also add that the yellow rubber covers were still intact. They are never used although they are slightly worn from people resting their thumb there. This was at around 1200 hrs.
I've got the same symptoms when there is no attachment on, it scared me the first time it happened. I thought the machine was getting ready to puke. I'll look in to that Countryboy, thanks!
I would ask the mechanic who repaired it for some more info but we no longer contract out the mechanics to repair our equipment. Its all done in-house now. Let us know what you find. :yup
Just thought I'd give an update here. This problem seems to have cleared itself, so I'm guessing moisture in the controls was the culprit. I'm going to have to remember to keep the windows closed when it's parked. Thanks for the help guys!!
Glad to hear it cleared up. :thumbsup
Glad, here, too, to hear it worked out. Let us know if she misbehaves again...
248B Problem Hi everyone, I just bought a 248B that runs very well, but doesn't move. It won't lift the arms or move the machine. Does anybody have any idea what this could be? We've tried wearing the seatbelt, parking brake, the wire is plugged in under the seat, etc. PLEASE HELP!!!! Thanks in advance. Mike
Welcome to HEF mikebrown! :drinkup Are you lowering the safety bar in the cab, if equipped? Is the parking brake actually releasing? Is there build-up/debris under the seat? Been awhile since I've been on ours but I don't think the seatbelt had to be buckled. You just need to be sitting in the seat with the safety bar down and the parking brake released. If you're doing all that and its still not working then you might have a problem with one of the switches or interlocks. If you want to rule out the seat switch then you can bypass the switch by connecting the 2 wires directly. CAUTION: I do not recommend leaving it this way, if the switch is the problem, because you are bypassing a safety feature. Hope this helps. :thumbsup
Here's a silly question, but did you push that rocker switch that unlocks the hydraulics and parking brake? It's in the upper left hand corner. I've had guys that didn't know about it, not all brands of machines are set up like that.
Its almost always dust or moisture in either the seat switch or the safety bar. They will work one minute then not the next. Test by bypassing them. You also need to check the relay for the ECM. Right upper side of the engine comp...waggle all the wires going into the relays....pull out the bunch plugs and check for corrosion.
Hi all, The seat switch and saftey bar would have to be working properly or the machine wouldn't start...right? It starts and runs great, just when you try and move the joysticks nothing happens. What does ECM stand for? Thanks a lot for the replies!! Mike
ECM = Engine Control Module, the computer that runs the engine.
Mike, you haven't said if the brake engaged light is going out?...its next to the rocker switch.
on my 236 i was using a rock hound on a yard when i lost all hydraulics and power to the wheels. motor ran fine but no power anywhere. there are two bolts that hold the pump to the motor, well they both backed out and the pump fell. there is a plastic disc that bolts to the flywheel that the pump splines in to. when the pump fell it eat the splines out of the plastic disc and lost every thing. i think the parts where around 300-400 bucks but had a friend that works for cat install it, i think labor was 700-800. he had to take the motor out to reinstall. i home it is something simple but if not this may be the problem
No, I know on Bobcat machines it will start and run great as you described, but will not move or lift until the hydraulics are unlocked with the switch in the upper left pillar of the cab and the safety bar is down. I don't think that the engine start is locked out in the same way. Paul
If all the interlock (parking brake) systems are working correctly and the there is no HYD functions, check to see if the fan is turning. If no fan rotation then the hyd pump coupler has failed, pump drive coupling has come off of the pump shaft or the implement charge pump has disconnected from the drive pumps.
Welcome to HEF CarterKraft! :drinkup
The 248s i worked on if i remember correctly would start fine without the seat belt on but would not move intil your seat belt was on and the lap bar lowered.
Steve, How do you like your 248 overall? It's one of the high-flow machines, right? I'm looking at a 2000 model 228 and I can't find much information on them. -john
I absolutely love my 248, it's the best decision I've ever made. Do an advanced search for 248 posts made by me, there's quite a few here.
Help with CAT 277 I know this is a post for a 248, but since I'm a new member and can't start new threads, I figured this would be the best place to start. I have a CAT 277 and there is a problem with the parking brake/PB relay switch. Everything runs fine - the arms even move. The problem is when I hit the PB rocker switch, the PB light starts blinking and and you can hear the relay switch start clicking. The PB switch not disengaging is preventing me to move. I bought a new relay switch which didn't work. I even swapped the relay switch from the safety bar, (which works), and still no luck. I pulled out all the wires to bypass the switch and I still get nothing. From reading the post here, I tried cleaning up the fuse box grid, but with no luck. I'm out of approaches and looking for help. Thank you.
Welcome to HEF safeguardguy! :drinkup
Thanks Countryboy!
Safe, did you solve your problem?
No not yet. Someone from CAT is coming over next week to fix it. I'll detail the solution.
Where would the relay be exactly