I have installed Ditch Assist grade control on my D8T by connecting it directly to the PWM valve, and it works, but only when I hold the ripper control to activate the on-demand pump. Where can I access the circuit to activate the pump via a switch so that the blade valve will constantly be active to work with the signals from the Ditch Assist control module?
Serial number?
KPZ001828
Unless you have a way of generating a PWM signal (because that's what the ripper control is sending to the Implement ECM) then you're batting a loser. This is not a simple "power on/off" circuit.
I'm not knowledgeable enough, but I will get there! Help me out here. So, the grade controller is sending a PWM signal to the valve, but since it is not "flowing" through the ECM the pump doesn't get the message. Is that correct? If so, then do I need to send it to the ECM in the same way the joystick is sending a signal to the ECM?? In other words, can I patch the harness into the joystick circuit instead of the valve circuit and achieve the correct result?
The ripper control is sending the signal to the implement module and you have piggy backed on to the valve. Some how you would need to duplicate the signal to activate the pump.
What about the supplier of the Grade Control system.? They should be the ones who specify how and where, and what type of signal they want as an input to/from their black box. Do you know this for certain.? Again questions have to be asked of the system supplier. No idea until you get some answers from the system supplier. Can you see a pattern emerging here.? TBH the best thing the system supplier can do for you is to supply a detailed electrical schematic of their system indicating where it should tie into the machine electrical/electronic system and what signals it requires.
Thanks for the replies. The supplier provided the harness to connect everything, but they did tell me they don't have it working properly. I installed everything and figured out it would work once I activated the pump by pulling the ripper control. They are not offering any solution so I'm on my own on this one. The controller is providing a signal to the PWM valve that I have it patched into, and it works very well so long as I activate the pump with the ripper control. Nige, I think you have touched on the problem when you said I need to find a way of generating a PWM signal to the ECM. Now, I just need to figure out where to connect to get that done.
The thing that worries me in all this is that, for the system to work, it appears as though a PWM signal to upstroke the pump has to be permanently present. That means that pump will be permanently upstroked, which it's not designed to do without going bang within a short space of time, at least as I understand it. I may be wrong. Somehow you need something connected to the Ditch Assist electronics box that generates a PWM signal output to the Implement ECM as and when the box decides it is necessary. There will be "spare" connections on the Implement ECM designed to accept inputs from a Cat Accugrade system if one was installed. However there is a chance that they operate over a CAN network, not by supplying a PWM signal direct.
That makes sense to me. There is a harness from when the Accugrade was installed. I need to learn more about what the Accugrade signal was and see if the Ditch Assist controller can duplicate it. Thanks for helping me think this thru.
There are fuel gasoline engine fuel injector testers that generate a PWM signal. ?? Just do a youtube search for PWM generator, lots of things pop up.
I had a look at the electrical schematic and the Accugrade Control Unit communicates with the Implement ECM via a CAN datalink. Deffo not PWM. Do you have any sort of electrical schematic and/or instructions from Ditch Assist that you can upload.? It would be interesting to see what sort of signal their black box outputs.
I will contact them and see if they will provide that info. I don't have anything myself other than the programing instructions for configuring the controller.
This may help you understand the electro-hydraulic implement system a little better. 1. Under each control lever (blade and ripper) there are two position sensors, one for raise/lower and the other for tilt. When all controls are in neutral all four sensors will have a PWM output of 50% duty cycle. 2. The implement hydraulic pump is a pressure-compensated variable displacement type. With the engine running but no command from the Implement ECM the pump is destroked into standby mode and the pressure in the system is maintained at around 400psi with miniumum oil flow. 3. If any implement control is moved away from neutral the signal from the associated sensor will change either up or down from 50%. Move the control in one direction the duty cycle signal will increase from 50% up to maybe 95% when the lever is moved fully, move it in the other direction the signal will decrease from 50% to maybe 5%. 4. The Implement ECM detects the change in PWM duty cycle from the control that was moved and commands the implement pump to upstroke, increasing the system pressure (and potentially the oil flow) from 400psi to 3500psi. The amount of control movement away from the neutral position will determine how fast the ECM upstrokes the pump. 5. As soon as the control is returned to neutral the duty cycle signal from the position sensor returns to 50% and the Implement ECM commands the pump to destroke back to the 400psi standby pressure again. Your original question was how to provide a PWM signal to the Implement ECM to get it to upstroke the pump so that the blade hydraulics would work. I hope that from the above you can see the system only upstrokes the pump as a result of a control lever input, whereas you were wanting to upstroke it permanently as long as necessary while required to control the Ditch Assist system. That would reduce pump life drastically and probably cause all sorts of problems with burst hoses between the pump and the control valve if they were subjected to a permanent 3500psi. What I would really like to know is what type of signal their controller outputs, but TBH they really should supply schematics, instructions, etc, etc,
I so appreciate the additional information. It has helped me greatly to understand the system. The DA controller is used to control a PWM valve I purchased with the system, but it will also control the valves directly on a JD tractor, presumably through the CAN Bus. Since you said the Accugrade also ran on the CAN Bus, I'm thinking the issue may be fairly simple. I had asked to have the system adapted to the dozer and they sold me a harness to do so, with the understanding that it wasn't perfected and that would be up to me. They did, however, want to learn what I did and possibly offer the option for others if I got it to work. It has been 3 years or more, and I was hospitalized with Covid since that time. Now I'm back at it and thinking it can be successful. I will contact their engineer on Monday and see what he can provide that may help steer this in the right direction.
If you want an electrical schematic for the tractor that is specific to your Serial Number just ask.
I talked with the dealer and he said they would benefit from having that schematic. The engineer told him he had not been able to obtain one. We may be getting somewhere !!!
If you purchased that system from them, they owe you all the help you need to install it and get it working. Its that simple. If they drag their feet on a schematic, then have them draw up one with easy to understand install directions for your machine.
Am I the only one who suspects what's going on here? The OP is trying to reverse engineer Accugrade. If it's for personal use, I'd say fine, but it seems likely that the info gathered here will be used by others. I don't know how proprietary the info he's looking for is, but we all know China has been ripping off legitimate technology for years. Just saying.
To answer your question...... YES, you are the only one that thinks trying to connect to the dozer hydraulic system is somehow reverse engineering Accugrade, which I don't even own!
To follow up....... It's working as I had hoped! The controller is now operating the blade function and I can't tell you what changed, but it is working. I did have the CAT tech come update the control files to the latest version since I had last tried using the Ditch Assist controller, which may have changed something to allow it to function. Either way, hey, it's working and I can doze wth the machine following the grade plan. Thanks to you, Nige. Your help in understanding the system and providing the files is greatly appreciated.