S/N RTB01915. Fan does not go to max speed when solenoid is unplugged. @Rjansky posted a question on a thread for a 140 grader. Really the diagnosis desverves its own thread. That either indicates a problem in the solenoid valve or maybe deepr in the system. SysOp & T&A documents attached. Electrical schematics coming via PM
Thanks Nigel, you're an invaluable resource to us all here! according to the RENR6077 manual "minimum" current input from ECM to the solenoid demands maximum hydraulic flow to the fan for high speed fan operation but it does not list min and max current parameters under which that solenoid operate. under no current(UNPLUGGED) at the solenoid, no change is noted in fan speed no matter the engine speed -which is inconclusive. either the hydraulic system has a defect causing no change OR the solenoid needs to see that "minimum" current value to engage the fan further- which "minimum" current is not noted... " If the current from the engine ECM to the solenoid is at a minimum, the solenoid valve will send the maximum hydraulic signal to the flow control." So bottom line is i need a manual way to engage the hydraulic fan system to maximum speed for cooling purposes. Until i can diagnose the no-fan engage situation.
Having briefly read through the SysOp (on my way out the door in a minute) if pulling the plug on the solenoid does not increase the fan speed then the first thing you need to investigate is whether or not the spool inside the solenoid valve could possibly be stuck. Also if you have adequate probes you could backprobe the fan solenoid connector and check voltage/amperage to see what's going on and whether it is being correctly controlled by the ECM.
Here is the troubleshooting procedure for the Fan Control solenoid circuit. The electrical schematic I sent you is going to come in useful sooner than you thought........
my first thought in diag was as you mentioned, backprobing to get a baseline idea. but in the interest of time right now i really just need full fan engagement prior to making it operate "correctly" AND because there have many hands in this machine prior to me i know the rabbit hole that diag and repair on this will cause..
I would be checking margin pressure or standby pressure on the pump. If margin pressure is low the output flow at any given pump pressure will be reduced. Could be as easy as tweaking the margin screw up a bit to see if it improves the fan speed.
good thought, especially if someone had backed it out or adjusted it not knowing.. but i would think it had minimum set points as to not allow it to be adjusted below a baseline that would still allow engine/cooling protection..
The spring in the margin spool does weaken over time dropping the margin pressure.
The issue as I see it is that if pulling the electrical connector on the solenoid did not put the fan to full speed then, until you find and address the problem, nothing else will. That's the simple facts of the matter regarding how the systme works. I think you may have to just roll your sleeves up and get stuck into it. For my part I would be looking very closely at the hydraulic side of the solenoid valve to make sure that it was moving when it was powered/de-powered. If does not move then there is your problem right away. From the table on Page 1 of the schematic the resistance of the coil for the solenoid valve is specced at 8.3 ohms. Maybe worth checking but I hardly think it is likely to be your problem. OK, you have 3 tests here, starting with LP standby. Margin pressure is the last test on the list. Personally I would suggest to test the LP Standby and HP Stall first, and look at the Margin pressure last.
Thank you Nigel, so that i have a better understanding of the complete system would you be so kind as to send me these 2 referenced docs? " Reference: For information about the hydraulic fan pump, refer to the Service Manual module Systems Operation and Testing and Adjusting,"Piston Pump (Hydraulic Fan)" for the machine that is being serviced."" " Reference: For information about the hydraulic fan motor, refer to the Service Manual module Systems Operation and Testing and Adjusting, "Piston Motor (Hydraulic Fan)" for the machine that is being serviced." verbiage comes from the "hydraulic fan system (RENR6077-01) document and i also have the others you previously shared. Thanks!
See the attached. Your fan motor is a gear motor rather than a piston one as per the text, but everything else remains the same.
thats perfect Thank You sir.