BlueBuck

Thanks for your continued help Dave. I tried jumping out the sensor with the engine cold and it turned fan on as you would expect and when I took the jumper off the fan would stop, but when the engine is hot the fan won't cut off.

The thermostat shouldn't cause the fan motor to keep running ..unless there is an electrical connection to it. (I was thinking from the standpoint of a stuck thermostat not allowing the coolant to flow and cool down enough to close the temperature sensor. This sensor is a normally open switch and closes when the temp reaches a high enough level, completing the circuit and turns the fan on). The temperature sensor should only trigger a relay to start the fan. Whether it also shuts it down when the temperature drops is the question. (Since this is a normally open switch which prevents the fan from running when its open, and when it closes due to the coolant temperature rise, starting the fan, I would assume it does shut the fan off when the coolant temperature cools back down enough to open the sensor and breaks the circuit from the power to the fan. Another reason I think this is because when I turn the engine off and the fan won't cut off, I have to pull the two wires off the temperature sensor thereby opening the circuit. All this is why I wonder about the thermostat) The fan breaker is likely just there to act as a resetable fuse, it could be integrated with the fan switch, but I don't know.. I would say the fan motor relay is the same as the fan switch; (This is what I thought) just different wording for the same item in different publications. Does the fan shut off when you turn the ignition off, (NO) and not start from cold until the coolant reaches operating temperature? (It doesn't start from cold for at least 10 or 15 minutes from an idle situation or until the temp rises enough) One thing I noticed in the wiring diagram I saw for the 750 is the fan motor shares a common connection to another sensor , I forget which it was , an air temperature one I believe. I wonder if those switches are wired so that the positive wire to the relays is hot and they are switched by the ground side , and a faulty ground in the circuit is causing them to trigger.. Where I get all the questions from is your statement the fan shuts down if you disconnect the temperature sensor. The problem you have with the fan has to be something in the circuit it is part of. Either something staying latch on, or maybe as I a faulty ground in that circuit i=or one connected with it . Isn't tracing electrical problems just a whole lot of " fun" ? More than one person has had a balding problem because of them. (I think you lose me in this paragraph)

> Is there a way to test the ECU? A good friend suggested that this may be the problem. Their a pretty expensive item, I notice. The wiring and harness seems to be OK as best I can tell. > I was wondering if a faulty thermostat could cause this problem? If I took the cover off and it was stuck in the open position when the engine is cold, indicating it was bad, do you think this would cause the fan to run continuously? > The wiring diagram in the service manual I purchased shows a Radiator Fan Breaker and a Radiator Fan Switch. Most every other reference I have seen refers to a Temperature Sensor and a Fan Motor Relay. Would it be safe to say the Radiator Fan Breaker and the Fan Motor Relay are the same thing and the Radiator Fan Switch and the Temperature Sensor are the same. Also on the wiring diagram in my service repair manual there is no reference to an ECU. In fact, I don't find any reference to an ECU. I purchased the service manual for a Kawasaki 650 4x4 Brute Force KVF650 2005 - 2009. What else might the ECU be referenced as? > If I'm not mistaken, the sole purpose of the temperature switch is to close when the temperature reached a certain status completing a circuit and thereby start the fan running and as the temperature dropped this switch would open and normally stop the fan from running. I'm about out of options within my capabilities other than these. I've been piddling around with this problem for 3 weeks now. So far I've replaced two parts that really weren't bad I don't believe. I know the temp switch was good but not sure about the fan motor relay, just that after replacing it the problem still exists.

Thanks Dave, I did that a few hours ago and am hoping to find the problem there. Thanks again

Well, I said I would post whether or not changing out the fan motor relay solved the problem and it didn't. My fan motor still doesn't shut off unless I pull the wires off the temp sensor. Does anyone have a wiring schematic for a 2006 Brute Force KVF650E6F ? I can't seem to find one on line so far. I didn't want to have to purchase the entire repair manual if I could keep from it.

Thanks Ajmboy, I appreciate it.

Thanks again Dave. I'll order a fan relay and if it solves my problem, I'll let you know. I did try disconnecting both the positive and negative wires I installed on the fan by-pass switch and that made no difference. Maybe the relay went bad, causing the machine to overheat instead of the overheating problem causing the relay to pop?

The initial problem was the machine overheated pulling a small bushhog, so I'm thinking that what ever caused it to overheat probably caused the relay to pop. For this reason, I am thinking the relay is good. I'm wondering if it might be a thermostat or water pump. I think the thermostat can be tested in boiling water but not sure how you would test a water pump.

Thank you very much for your suggestions.

I didn't rewire the thermal sensor but just replaced the old one. I'm pretty sure both the old and new sensors are good ones. Like I mentioned before the fan relay was popped when I first discovered a problem but not sure what caused it to pop.

I appreciate your response. I ran a hot wire from the positive side of the battery to a 10 amp breaker then to a switch and finally to the positive wire of the fan. I also ran a ground from the negative wire of the fan to a bolt on the frame for a ground.

My fan on my 2006 Kawasaki Brute Force 650 KVF650E6F ( less than 200 hours on it ) overheated when I was bushhogging a small clover plot for deer hunting. I immediately stopped and let it cool off and proceeded to ride it to another part of the farm without the bushhog and within a 100 yards it showed the overheated light again so I loaded it back on the truck and quit using it. Once I got home, after a day or so I used it a few times around home pulling a small trailer to pick up sticks and such and didn't have any problem. I realized the problem was most likely still there however and I needed to get to the bottom of it. I discovered the fan was not coming on. The first thing I noticed was that the fan relay was popped out with the red button out. I pushed the button back in and replaced the heat sensor thinking this was the problem based on some videos I watched. Not knowing that much about the mechanics of the machine, I was trying to diagnose and repair the problem with help from these videos. I did install a switch circuit so I can run my fan whenever I choose now. Unless I keep my heat sensor disconnected however, the fan won't cut off after turning the engine off. From the time I turned it off the fan still hadn’t cut off after 20 minutes so I pulled the wires off the new heat sensor and the fan stopped. I immediately put a multi-meter on the sensor and after one minute it opened but would not do it until I disconnected it. That makes me believe the brand new heat sensor is good so is it possibly the fan relay since it was originally popped or more likely something more serious? While the fan was running, I took a wrench and tapped on the thermostat housing , the sensor, the wiring harness and various connections just per chance but nothing. Like I said the machine didn't seem to overheat unless under a strain like pulling the bushhog and not sure if it will do that again since I installed the heat sensor but I don’t believe the sensor was the problem. I hot water tested the old sensor and it checked good and the new sensor tested good with a meter both hot and cold. The fan won’t cut off with the heat sensor plugged in though. Can anyone advise me as to my problem?