I have loader that is experiencing a failure raising the bucket. Everything operated fine during the last use. When I started it for the next project I tilted the bucket back then pulled back the lever to raise the bucket arms. The bucket did not lift and the driver alert (!) began flashing. When I pulled back the lever to raise the bucket I could hear/feel something try to engage before the light began flashing. Once the warning displayed it does not make the sound when pulling the lever back. First thing I checked was the hydraulic fluid and it was right at the low level so I added hydro fluid thinking that must be the issue. This did not fix the issue. The loader drives OK, the bucket does tilt, but it will not raise. When I shut the unit off and restart the warning goes away and will not reappear until I try to raise the bucket and then the cycle repeats. Any troubleshooting help is appreciated. I'm a good distance from any service/repair center so hoping to isolate the issue if possible. Thanks in advance for any guidance with this issue.
Please can you supply a machine Serial Number. I would like to see how it was originally built. Can you post a photo of the panel located in the upper RH corner of the cab.? Does the image below look like your alert panel.? If so which lamp are you referring to and what colour is it.? Steady or flashing.? Are there any other lamps illuminated.?
The light that flashes is #1 in the image you posted. It is yellow and it flashes. In my manual it states there are three levels to this warning, a solid light alert, a flashing light alert, and a flashing light alert with audible alarm. I am getting the second (flashing with no alarm) when I attempt to raise the arm. There are no other warnings displayed and everything else seems to be working fine. The serial number for the unit is RED00572. Not sure if it's helpful but the unit has about 350 hours on it. Thank you
Does the light go out when you release the control lever back to neutral.? Can you post a photo of your RH upper panel please. You may have the type of panel that can be used to access Diagnostic Codes in the electro-hydraulic system and that could be very useful.
Once I pull back the lever to raise the arm there is a brief delay (about 5 seconds) before the alert starts flashing. It continues to flash after I release the lever. It continues flashing until I shut the unit off. This unit doesn’t have a panel on the right side. The left side panel has fuel, key, brakes, hours and the warning lights.
Fair enough. It's going to require testing some of the wiring harnesses in that case. Are none of the implement functions (lift & tilt) working.? Does your machine have a cab door.?
The bucket will tilt up and down, it will not lift when I pull back on the lever. Is this likely related to something electrical? My knowledge with this is very limited so I figured it was related to the low hydraulic fluid level. Appreciate your assistance.
That narrows it down a lot. Good in one way but not so good when you said that your electrical knowledge is limited. The next thing I was going to suggest would be to compare the electrical signals from the implement joystick for the lift/lower and tilt/dump functions. To do that you are going to need a multimeter capable of measuring duty cycle.
I have and know how to use multimeter, and Im very good at following instructions.
Does your multimeter have the capability to measure duty cycle.? Some do, others don’t.
Does Cat have interlock solenoids like a bobcat?
Yes and no. But the fact his tilt function is working but lift isn’t is telling me to look at the PWM signals from the RH joystick.
I had to travel for another quick project and will be back at this site to troubleshoot in a few days. I will confirm my tool can measure duty cycle. If not, I will borrow or buy one.
I made it back to this loader today and spent some time checking a few items trying to resolve this issue. As a brief review: After starting and releasing the break the loader would allow me to tilt the bucket but when I attempted to raise the bucket it would not lift and I immediately would receive a flashing yellow alert. although the bucket would not lift I noticed the feel and sound of hydraulic pressure being engaged. I checked the hydraulic fluid and noticed it was a little below the minimum level. I filled the fluid and started the loader again and had the exact same result each time. That is when I posted in this forum. stick Since sitting for a few days I started the loader today to take videos of the issues. After starting and tilting the bucket I attempted to lift the bucket to trigger the warning light. The light would not trigger this time although the bucket did not lift. Also different was that I could hear and feel the hydraulics remaining engaged as log as I pulled back the stick. I repeated this a few times and then arm started to lift but only raised a couple feet and I quickly lowered it to test that movement. It wouldn't raise again once lowered. I stopped trying because I wanted to post this update and see if anyone feels this helps isolate the issue. I know very little about these hydraulic systems but feel like the loader sitting for an extended time with low fluid may have introduced something that would restrict or limit the hydraulic arm from lifting. I've read a bit about air or debris in lines or filter but don't know if that is possible with the conditions I've experienced. Any help is appreciated.
Unlikely. Even with the oil level a bit on the low side (provided the oil was actually visible in the sight glass) this would not be sufficient to trigger your symptoms IMHO. The implement system on your machine is electro-hydraulic. An electronic signal goes from the joystick to the ECM which in turn sends a signal to the solenoids on the main control valve that in turn sends hydraulic oil to the appropriate cylinders. For that reason if I was working on it I would make sure that the electronic side was working correctly before moving to the hydraulic side. As you have little or nothing in the way of testing equipment maybe we need to think outside the box, at least for a start. This test will require the cab to be raised to gain access to the main implement control valve that is mounted on the inside of the RH frame rail. The inside of the valve will have three pairs of solenoids in a installed on it, as shown below. The lowest pair of solenoids (#4 arrowed) control the bucket lift function, the centre pair (in the rectangle) control the tilt function, and the upper pair control the AUX function. Unplug the electrical connector from the lower solenoid and plug it into the centre solenoid directly above it, installing the connector that was removed from the centre solenoid into the lower one. Do this for both the LH and RH rows of solenoids. Now you have to be VERY CAREFUL . What you have done is swap the connections to the lift and tilt solenoids, so when you move the joystick from the neutral position to either raise/lower the bucket should tilt one way or the other, and when you move the joystick for the tilt function the bucket will either raise or lower. Do that and report back exactly what happens.
Thank you for this information. I will perform this test soon and share the results.
Check out this thread showing how easy it would be to get into electronic diagnostics if you had the optional RH panel installed. The panel in the photo is retrofittable to your machine BTW. HeavyEquipmentForums
Hello - I made it back to this unit to complete the test you noted with the solenoids. While messing with the tilt to get it out of the shop I discovered some changes so I wanted to share them before progressing. Also, I now have a multimeter that can test for duty cycle if that is required. As a refresh - originally the bucket would tilt but not lift. As soon as I pulled back the joystick to lift the machine displayed the driver alert (!) began flashing and it would not lift. If I shut off and restarted the machine this cycle repeated. Then on my last visit to the site when I pulled back the joystick it would not raise but the alert would never flash when I tried to lift the arm but suddenly it did raise the bucket a few feet and then it stopped. This was my last post before leaving town for another project. Today I made a trip back to the site to reverse the connections on the solenoid and after backing it out of the shop for safety I wanted to test it again to see if the same results were experienced. The same results happened with the tilt working and it would not lift the arm when I pulled back on the joystick but if I pulled back and to the left it would raise the arm. It lowered the arm as normal by pushing the joystick forward. I repeated this 4 or 5 times and then it stopped working. At that point the (!) began flashing again and this time neither the tilt, lift or lower would not work. If I shut it off and restart I can repeat this cycle (which I had to do to lower the arm so I could open the door). Every time I repeat this process it will only raise the arm by pulling back and to the left. I wanted to post this update before attempting the swapping of the solenoids since the issue now includes the failure of the tilt function too and not just the raising of the arm. I also have a multimeter for testing if there is a better test to run to diagnose the issue. Thank you again for all of your assistance with this machine. You knowledge of these machines is exceptional and it is helping me understand the issue much more. I have videos of this process if that would be helpful. The file may be too large to post or email.
Now that you have an appropriate multimeter the easiest and least intrusive test at this point would be to measure the duty cycle output of the fore-and-aft and side-to-side position sensors in the joystick base. Locate the electrical connectors below the joystick base. There will be a 6-pin and a 12-pin; you need to focus on the 6-pin illustrated below. Set the multimeter to measure duty cycle and turn the key ON. It is not necessary to start the engine. For each of the 6 Steps below take the measurements multiple times to ensure consistency. All measurements should be taken by back-probing the connector. You can't disconnect it to measure. The Pin Numbers should be moulded into the body of the 6-pin connector. Pin Numbers can also be confirmed by relating them to wire colours. 1. Measure the duty cycle between Pin 3 (X-Axis) and Pin 2 (Ground) with the joystick in the centre. 2. Repeat the measurement with the joystick moved all the way to the left. Return the joystick to the centre and confirm that the duty cycle is the same as what was measured in Step 1. 3. Repeat the measurement with the joystick moved all the way to the right. Return the joystick to the centre and confirm that the duty cycle is the same as what was measured in Step 1. 4. Measure the duty cycle between Pin 5 (Y-Axis) and Pin 2 (Ground) with the joystick in the centre. 5. Repeat the measurement with the joystick moved all the way forward. Return the joystick to the centre and confirm that the duty cycle is the same as what was measured in Step 4. 6. Repeat the measurement with the joystick moved all the way backward. Return the joystick to the centre and confirm that the duty cycle is the same as what was measured in Step 4.
I removed the parts so I could position and access these connectors. There is good visibility to the back of the connector and labeled wires but didn't realize how tightly sealed the wires would be in the back of the connector. Is there a best tool to use for the probe? When I researched there were various types of probes available (piercing, probe, & spoon). With fairly easy access to the joystick is there a way to test it if removed? I didn't know if a service center can test or if they would need the machine with the joystick connected.
Spoons are the best thing in my experience. Look for Cat Part Number 7X-1710 or the aftermarket equivalent.
I want to thank you for the guidance provided with the issue on my loader. Since the unit was in a remote area and I could only make it there for very limited time I removed the right joystick and brought it to a service center for testing. The service center watched my videos of the issues and said they believe it's a bad joystick and stated it's cheaper to replace the joystick with a remanufactured one than to do troubleshooting on it. With my limited knowledge I accepted their feedback and bought a replacement. After installing it yesterday and running the unit for a series of tests it appears to be working good. Thanks again for all your help.