Hello to everyone! Im new in this forum. Seems to be a good one I have a 2002 Bobcat A-300 that is getting an error code 38-74 uncommanded right wheel speed error ON. After it has run for just a few minutes,testing left wheels are ok, boom is OK bucket motion OK, A300 all steering wheel OK, it cuts off when you move joystick to move right wheels forward or rear. Spent almost a thousand bucks at bobcat dealer in Peru and they have not fixed the problem. I know they disassembled and check both hydrostatics pumps and its housings control pumps, motors on both sides are checked, auxiliary pump checked, auxiliary valves box (booms and attachement spools) checked, radiators and wiring harness checked, all steering valve box checked. My problem is complicated . Anybody know what this code is, and have any suggestions on how to fix this SERIOUS problem? many thanks for your kind support and sorry for my basic english. Alvaro
Hello , i know this is an older thread but i was wondering if you found out what the issue was that was causing this error. I have a 2004 A300 that is giving me the same error but on the left side. I have a repair manual , remote start tool, and the software for diagnostics. I have calibrated the wheel sensors and alignments, im still troubleshooting it and am leaning towards a bad solenoid or a valve that is not seated allowing hyd flow to the drive. Thanks for any help.
I don't have specific information on the error code but when the Op mentioned that the problem would surface when the joystick was moved it had me thinking about the early A300 issue. The early version of the A300 came with a round base joystick. They were prone to failure. I have an '06 (also came with the round base sticks) and they were replaced (under warranty) with the newer square based joysticks when they failed. This was done back in '06 and I have nit had a problem with them since. The machine has over 5,000 hours on it now.
i took the joystick apart and found a couple wires in the harness were cut and then just tied together, i soldered them and replaced the joystick. I also removed all 4 steering valves and replaced the o rings. I started the machine up and it is still doing the same thing. When i have the diagnostic computer hooked up with the joystick screen pulled up it shows that the joystick is in the home position . when i hit he green operate button i see that the flow to the left side shows 3gpm of flow and then it throws the code and shuts down. It seems like as soon as the brake is released when i push the button its getting flow to the wheel motor. Im still leaning towards something mechanical, maybe its electrical but im not showing anything with the diagnostics.
hi, there is one sensor on each carrier. one for left, one for right. the sensors send the motor-carrier speed to the computer. in this case, your loader sensors, send incorrect information. check the sensor wiring on the carrier. it have 4 wire. maybe the cover of wire damaged and it shorted to ground or voltage. the sensor is exactly above the carrier. it covers with the oval shape metal plate and fixed with 2 of 10mm bolt
I located the sensor and checked it, it appears to be ok, i did remove sensor from the housing but i left it plugged in, when i started the machine and pressed the operate button it did not cut off this time. The problem is without pushing the joystick, the left two wheels are slowly moving but the right wheels are not. When i push the joystick forward or reverse nothing changes. I am thinking there is a problem with the pump controllers or maybe even the hydrostatic pump. I went through the manual and tried going through the hydrostatic controller calibration, I made it through the process where you zero out the joystick, but when i start the machine to calibrate the controllers, nothing changes , the left wheels slowly move and the right wheels do not. Does anyone have any other suggestions of what i might can try and troubleshoot, im about tired of screwing with this thing and am seriously thinking about just parting this thing out.
dear friend, A300 is a difficult machine to diagnostics. as it has a steering wheel , is has a electronic differential , i mean , the AWS controller compensate each machine side speed according to wheel angles.any way, if the wheel start to move without operation of joystick, the problem is inside the pumps. you must to put 2 pressure gauge in two side of pump and adjust the natural position of swash plate. after that you can do the electrical calibration it is a little bit difficult, i recommend to ask your dealer to do this.
i have washed my hands of this project, i sold it..... its messing with my fishing time.....lol, i will be posting a Bobcat Melroe remote start tool and software for sale shortly.
If you still have the tool hit me up I just got one of these into the shop and it is driving me crazy