850j engine overheating under load

[viktor]

overheating engine under load .throwing 1071.5 code.some one can help

 

[mg2361]

Welcome to HEF viktor!

Need a serial number to get the correct information.

A 1071 code is a failure of the fan drive circuit.

 

[viktor]

1t0850jxkbd207322

 

[viktor]

ok thank you. wondering if someone has a wiring diagram.hi everyone.

 

[mg2361]

According to your serial number you do not have a reversing fan, correct? That means the solenoid that controls the fan speed is mounted directly on the fan motor. There are only 2 wires that go from the solenoid (H02 Green and G11 Black) to the transmission controller (yes, the TCU controls the fan). It takes 0 voltage to operate the fan at full speed and then varies the voltage (pulse width) up to slow the fan down. So your solenoid "valve" is either stuck in the bypass position or there is voltage getting to the solenoid when there shouldn't be (most likely since there is a code). Solenoid resistance spec is 27 - 30 ohms.

Unplug the solenoid at the fan motor (you will have to tilt the grille to gain access) (engine off obviously). Put your grille back into place. Then start your engine and your fan then should operate at full speed. Try working your machine with it unplugged to see if your heating issue goes away.

 

[viktor]

thank you very much I going to try it out.

 

[Andre van Greunen]

Only operate in 1st gear when pushing a heavy load.
Use the other gears for lighter loads or for travelling in forward and reverse

 

[viktor]

hi my solenoid is beside the a/c compressor.and I getting 0 voltage at the black wire I have ground at black wire.and nothing coming from the green wire when I unhook the connector.when I connect the connector to the solenoid I have 0 voltage at green wire and black wire i have ground. but the fan speed work fast.

 

[viktor]

and I changed the solenoid already and still have the code coming up 1071.5

 

[Andre van Greunen]

Hold in the menu button to go into service mode, scroll to active codes, delete codes. If the code come back you have a problem.
The job for the solonoid is to ramp up fanspeed and decrease it, it gets voltage from the ECU, 5V. The temp sensor for the engine sends signals to the ECU. The ECU send signal to the solonoid, milivolts to open and close.
Check wire continuity from the solonoid to the ECU. Check the terminals carefully. I use a paperclip to see if it is not stretched open. Ive seen some guys push the multimeter probe into the terminals, stretching it open, then no contact.
You can check the engine thermostats. Make sure the earation line from the thermostat housing is open.
Ive seen in Zambia operators push in the wrong gear causing engine overheating.

 

[viktor]

so my 850j is still overheating.i changed the thermostat and still heating up but only if you push hard and fan is at high speed running. after few min is cooling down right way.and it wastes at the red side I tock my heat gun and checked rad hose lower and and upper one only 5 degrees different I had 90°upper and lower was about 85°.I cand find the tcu I want to check the wire if is brocken.or shorted.

 

[Andre van Greunen]

Temp difference top to bottom should about 12°C.
You first have to go into service mode on the monitor and clear the active code, see if it come back when you operate in FIRST gear please!!
The ECU is located behind the seat, righthand on top of the dash.
Could even be a fan motor that is worn.
What RPM does the fan run?
Check the radiator cap, did you change the coolant, is the radiator fins clean, no obstructions?
Is the aeration hose open, not blocked. Its the thin hose going to the expansion tank...

 

[sfowler]

Temp difference top to bottom should about 12°C.
You first have to go into service mode on the monitor and clear the active code, see if it come back when you operate in FIRST gear please!!
The ECU is located behind the seat, righthand on top of the dash.
Could even be a fan motor that is worn.
What RPM does the fan run?
Check the radiator cap, did you change the coolant, is the radiator fins clean, no obstructions?
Is the aeration hose open, not blocked. Its the thin hose going to the expansion tank...

I'm not sure why you keep saying First gear. The 850j is a hydrostat--there are no gears or transmission. The selector is basically a speed control. In very general terms, the hydrostatic system is load sensing and compensating and if things get in a bind it will 'kick you out' and relieve the system before any harm can be done or before dragging the engine down or stalling. You can essentially choose the highest speed range you desire to work at (from 1-3) and the drive system will automatically adjust for load increases. As the machine slows due to increased loading I have never seen any appreciable rise in engine temps or hydrostat temps. As an example, for dirt pushing I'm usually set at 1.5 to 1.6, but as I get in tough spots or am bulked up at the end of a push the machine can be barely moving. I have my throttle setting maxed out at 2285 rpms at the start of the day and I work with the decelerator pedal in the mode where it controls machine speed and does not act as an engine decel. My engine rpms stay within a 200 rpm range all day, my speed setting never changes, but my machine speed can vary to large degrees depending on loading or whatever I'm doing at the moment. What I'm trying to say is that I don't manually shift down as I get loaded and the engine does not drag down. I just let the hydrostat do what it was designed for.

Also, you should not have to delete the codes. An 'active code' will disappear if you turn the machine off and the code should be stored with a time stamp for reference. When you restart the machine, an active code will only appear if the problem occurs during the operation cycle.

I should mention that I'm in a part of the world where we are routinely at/over 100F for a large part of the year. I usually pull a root plow which puts an extreme demand on the machine. At 105F I pulled the root plow all day and never had the coolant temp over 206F and I had the speed selector set at 1.5, but there were many, many times the machine was barely moving or periodically standing still.

 

[Andre van Greunen]

If you keep operating the machine going into overheating your engine is closed to being cooked.
My best advice consult your closest JD dealer.
Tech must come with service advisor and an operators manual.

 

[mg2361]

hi my solenoid is beside the a/c compressor.and I getting 0 voltage at the black wire I have ground at black wire.and nothing coming from the green wire when I unhook the connector.when I connect the connector to the solenoid I have 0 voltage at green wire and black wire i have ground. but the fan speed work fast.

If you have "0" volts at the solenoid either the H02 Green wire is shorted to ground, open or the driver in the controller is bad. But no matter which scenario you have the fan should be turning full speed with no voltage.

The only way to check that for sure is with a photo tach since that machine does not have a fan speed sensor. Fan speed should be 1450 rpm with the solenoid unplugged. If you do not have 1450 rpm then the fan pump needs to be flow tested.

If you only have a 5 deg C drop on the radiator temperature that indicates an air flow issue, whether it be fan speed, plugged up cooling package or missing baffles around the cooling package.

 

[viktor]

good day.i got my 2011 850j back to the shop from the field and it's still overheating. I still have the code tcu 1071.5.for the forward solenoid fan I have black wire g11j.and the green wire no number on and the both go to the front to the radiator. and for the reverse solenoid the black wire is z111 and the black wire is going to the front to and the green wire no number to and is going in to the harness and to the back somewhere. so can someone give me the wirring diagram pleasepid # 1t0850jxkbd207322.and I follow the wire wich going to the front ther is to plugs open connectors and the laying on top the radiator and the other wires for horn and lights ther is no wore going to the fan motor.or pump on the fan.and the 2 wires on top the radiator the black ones one isg11h the other one g11d.

 

[mg2361]

Did you run your machine with the fan solenoid and the reversing solenoids unplugged to see if the overheating goes away?

 

[viktor]

yes still overheating

 

[mg2361]

Do you have access to a photo tach to check fan speed?

 

[JL Sargent]

is the radiator fins clean, no obstructions?

This bears repeating. Make sure the outside of the radiator is clean.