I have a the above excavator and it suddenly started bogging the engine down when applying full hydraulics regardless of which pump motor is engaged. It does this with the drive motors or any of the digging cylinders. It also blows the #1 fuse as soon as the key is turned on. I replaced fuel filter, hydraulic filter that's in the main reservoir and I also checked to ensure the turbo spins freely. Does anybody have any idea why the hydraulics would bog the engine down. It will kill the engine if you apply constant pressure to any of the hydraulic control systems. Please help is you can. Also, if anybody has a service manual that I could take a look at that would be most appreciated.
If you are blowing a fuse you have a dead short in a circuit. It's likely that the circuit controls pump stroke in some fashion. I'd start looking a wires real close back in the pump compartment to start with and then start checking solenoid coils and connections. Can you describe which fuse is blowing. Generally they are in a stack and you can count from one end or the other in which slot the fuse is plugged into. Let us know and maybe one of us has a book with a diagram that fits that machine and can tell you what circuit that fuse protects.
At a loss... Thanks John, there is a horizontal row of 15 fuses on the right side of the cabin about shin high. The first fuse closest to the front of the cabin is the one that's blowing as soon as you turn the key on. Some more history - about three weeks ago the auto throttle stopped working. I checked the voltage at the throttle control governor motor and there wasn't any even though all fuses were good at that time. I decided to bypass the speed dial, governor motor, etc. and had a manaul throttle cable made. It and the machine have worked perfectly up until a couple of days ago when the hydraulics started killing the engine. I also checked the banjo filter that's in the fuel supply line going to the fuel pump/primer assembly. It looked as though fuel flow was ok coming from the fuel tank but it wasn't just flowing out. My next check is to see if there is a fuel filter of some sort in the fuel tank itself. Is there some sort of flow control for the hydraulics? The machine cranks right up and appears to run fine until you put a load on it. You can ease into the hydraulics and it works fine but when you request full hydraulic power it bogs the engine down and will even kill the engine unless your release the hydraulics. It doesn't matter which pump you exercise either. It can be the drive motors or any of the boom and digging systems. I bought this machine for one purpose and that is to build a lake on some land I have. I'm about 2/3 of the way having the lake completed and almost ready to dig the core and then this happens. Any help you can offer is most appreciated. Thanks again, John.
From what I see in one of my old books the number 1 fuse is the power source for the pump controller which is located in the boom side console behind the operator's seat. You have to remove the plastic directly behind the seat in order to see the computer box. As I recall there were two types. Older machines had a single computer, one was the pump controller and the other is the engine throttle controller. On later machines those two were all put in one box. You can disconnect the harness on the computer, put the fuse in a see if it blows again when the key is turned on. If it doesn't I would probably leave the key on and then plug in the harness connectors and watch for the fuse burning though again. If the fuse blows out with the computer unhooked you likely have a wiring issue. Many times people put other components like heaters and radios in the machines and powered them up with any hot wire they could find. Hopefully you find something there but I kind of doubt it. Worst case is something is shorted out inside the computer. I have removed the computers before and opened the case up to look inside. Sometimes you will see blackened components on the circuit board that might confirm the box is the problem. PM me and I think I might be able to send you some more info.
Thanks again John. My internet has been out for 3-4 days and that's why I haven't gotten back. There is two sealed cases behind and to the right of the seat so I'm assuming that mine has two controllers. One thing that I did see this weekend is there is a solenoid that controls a hydraulic vavle back by the main pump. It has two lines in and two lines out. When the fuse blows I lose voltage to that solenoid. But when I bypassed the controllers and ran 24V directly to the solenoid it didn't do anything. The fuse will blow though even this solenoid is disconnected. I got 9 ohms across the solenoid but again it doesn't do anything when I send 24V directly to it. It looks like a bad solenoid but there must be something else wrong with the controller or the wiring since it still blows the fuse.
Nine ohms is just about right for what the solenoid should read as I recall. The four wire thing is odd because a solenoid will usually only have two wires. Maybe you are looking at the throttle control motor? There should be a stack of solenoids either behind the cab or in the pump compartment. PM your email address to me and I might be able to send of info. A photo of the component and the fuse panel might stir up some memories of simple things I've seen in the past. One other thing, which engine is installed in this machine? Does it have a single valve cover or six individual valve covers?
The solenoid only has two leads but the solenoid doesn't pick when you apply 24V directly to it. I disconnected the throttle control motor a few weeks back. It seems like my throttle controller went out and I managed through that with a manual throttle cable but the hydraulic controller is now having problems it appears. Is there a main computer on controller that is connected to the throttle controller and the hydraulic controller? I have a service manual on the way so hopefully that will help pinpoint the problem. I can't get the file uploader to work to attach a picture of the solendid but it's inside the main pump door on the right rear side of the machine...
What you are describing I think is called the LS-EPC solenoid valve. As I recall that only comes into play when the pump loads up the engine more than there is horsepower to carry and backs off the pump to maintain maximum torque from the engine. It is controlled by the computer. In normal operation as I recall it doesn't come into play. There are two toggle switches in the fuse compartment of the cab as I recall. One is a swing brake release switch and the other is a TVC prolux switch. Basically it bypasses the computer and sends a reduced steady current to the TVC solenoid valve on the pump. It allows the machine to operate at reduced performance when the computer is malfunctioning. You should shift both those toggles and try installing a fuse to see if it blows out.
Thanks John. I switched both of the toggles and put a new fuse in. It blows as soon as you turn the key on regardless of which position these two toggles are in. As soon as it blows the fuse it sounds the beeper alarm. I don't have the governor motor connected but I wouldn't think that would have anything to do with this number one fuse blowing. Any ideas where else I can look? Thanks again John...
I would now try to find the diodes and check each one with an ohmmeter. The stack of them are taped to the main wiring harness in the back corner of the cab. Each one has two wires going into them and black tape holding the diode and connection to the wiring. There is a snap hook that holds the diode in the harness connector that you have to press to release the diode. You check them with an ohmmeter. Touch the leads to each terminal and then reverse the leads. There should be continuity one way and not the other if the diode is good. There is a number on the wires coming out of the harness on each diode. Record any that are bad and let us know. Other than this you will have to go through the machine inspecting the wiring harness for problems, damage, burn spots, holes and corrosion. These type of failures take copious amounts of time and study to find and usually little time to fix.
D13 is bad. The other 8 or 9 checked good.
Note to JohnC Hey John, anything else that I need to do before replacing D13?
JohnC, I replaced D13 and it still blows #1 fuse. D13 is still good after fuse blew. I will try disconnecting controllers tomorrow and see if fuse blows. Thanks for all your guidance.
Diode D13 is in the battery relay circuit that powers up the throttle controller. The is likely the reason you throttle controller doesn't work. Fuse number one is power feed for the pump controller and fuse number two is power feed for the throttle controller. I just saw another power lead in my schematic that goes to the air conditioner that is powered from fuse 1. The air conditioner is behind the operator seat and you will see it when you remove the plastic cover. There will be a four wire harness connector going into the unit somewhere that you should unplug and then try the fuse before messing with the controller connections.
JohnC, I bypassed actually but still bows #1 fuse. I disconnected c01, c02 and c03 one connector at a time with #1 fuse blowing each time. I then disconnected h01 and fuse doesn't blow. I'm trying to locate c07, c08, c10, c13 and c4. I will disconnect one at a time and check fuse. Does it sound like I'm headed in the right direction?
I bypassed air conditioner. This spell check thing typed actually instead of ac.
Ho1 is an intermediate connector and the harness goes back to the pump control solenoids. There are two solenoids on the pump itself and two pump pressure sensors usually on the main control valve. You ca check all those with an ohmmeter first and if they have no resistance hook it back up and test to see if it blows a fuse.
JohnC Hey John, I found the two switches on the main control valve and checked those with neither having continuity, which I'm guessing is normal. #1 fuse blows with both disconnected. I reconnected those but I haven't been able to locate the two solenoids on the main pump. Any idea where those are at? I have looked everywhere in the back right compartment where the pump is but can't find anything but that LS valve and solenoid. It has nine ohms across it so I'm guessing it's good.
The coils are in the middle of the pump between the governors. You will see where the front half and back half of the pumps join together and the coils are there.
JohnC, Been tied up at work. Both of the tvc pump solenoids check good and the fuse still blows if both are disconnected. It has to one of the circuits off of the H01 connector, right? If I unplug H01 it doesn't blow the fuse. When it says H01 on the wiring diagram and right beside that is S16 in parenthesis. What does the S16 mean? Any additional direction you can provide is most appreciated.
JohnC, do you know where the prolix resistor c06 (s10) is? Could that be the problem?
The prolux resister is in the console in the cab mounted forward of the control computer. It is an aluminum box looking thing. The CO6 connector is right above the box. I don't know what S16 means and I don't see it in my materials. An S usually refers to some kind of switch and the highest indiction is SO6 in my book. Your problem sounds to me like a wiring issue. The HO harness runs back to those components on the pump that we talked about. What I have done in the past was start checking each wire terminal in the HO1 connector for contact with ground using an ohmmeter. Once you find the shorted wire you can refer back to the wiring diagram to find out the function of that wire and a likely place it might be finding a ground connection that it shouldn't have.