Kawasaki Brute Force Radiator Fan won't cut off

[BlueBuck]

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?

 

[davefrombc]

Are you sure  you  wired the  new sensor  in  properly?  It sounds like  it is latching  on. There  should be no  power to  it or the  fan relay  with the  ignition turned off... I would suspect  your  bypass circuit  that  you wired in may be  causing the  problem.

[BlueBuck]

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.

[BlueBuck]

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.

[davefrombc]

Somehow the relay  is getting voltage  to  stay locked on.  Something in the  circuit  is feeding   power to  the  relay   even  with the  ignition turned off (some  kind of feedback  loop that  you  break  by  disconnecting  the  sensor). Try  disconnecting  your bypass and see  if that   fixes  it. It also  could be  a  problem with the relay  itself. I can't  help further beyond  those suggestions .

 

[BlueBuck]

Thank you very much for your suggestions.

[davefrombc]

Let  us  know  when  you find the  problem..   I  never thought to mention it before, but it might be  the relay itself at fault.

 

Edited May 27, 2017 by davefrombc

[BlueBuck]

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.

[davefrombc]

Water pump  can't run if the motor isn't  running unless it is electric,  and fan shouldn't  run   unless the water temperature  is over  it's  turn on  point.. If  you  haven't  changed the   relay,  that's what  I'd suspect  the  most.  If  it  has an  unswitched  hot  wire then  it could be feeding  the   power to the sense  side of it    and keeping it  on. Something  in the  fan  circuit  is  getting  power  with the  ignition  off.  The  water pump  runs  with the  motor.  The  fan  should only  run  when the  motor  reaches it's turn  on temperature.   You  changed the   temperature sensor, so  most likely culprit  is the relay itself.  I  can't see  an  electric water pump  or  any  other circuit feeding the  fan. Have you disconnected  both the  hot  and ground  jumper wires  you installed ? Your  extra  ground wire could be the  problem   if  for some reason   the relay  in that  circuit  switches the ground rather than the  hot wire ..  I'm  only  giving you  stabs in the  dark  since  I don't have an electrical  schematic of your  circuit to  make  guesses  from. 

[BlueBuck]

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?

[davefrombc]

That sounds more  logical to me .

 

[Ajmboy]

* Topic moved to Kawasaki ATV Forum.

[BlueBuck]

Thanks Ajmboy, I appreciate it.

[BlueBuck]

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.

[davefrombc]

 

Check the  shop  manuals  posted for the  Brute  Force 750..   The wiring is most likely  very much the same for the  650.

Here is the  link to  download  the  2008 manual  for the  750  in the  forum's downloads  section ( Mouse over Browse and click  Downloads to  find the  lists  of all  the  manuals  and information there)  : 

 

[BlueBuck]

5 hours ago, davefrombc said:

 

Check the  shop  manuals  posted for the  Brute  Force 750..   The wiring is most likely  very much the same for the  650.

Here is the  link to  download  the  2008 manual  for the  750  in the  forum's downloads  section ( Mouse over Browse and click  Downloads to  find the  lists  of all  the  manuals  and information there)  : 

 

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

[BlueBuck]

> 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.

[davefrombc]

The  thermostat  shouldn't  cause the fan  motor  to  keep  running ..unless  there  is an  electrical  connection to  it.  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.  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;  just different wording for the same item  in  different  publications. Does the  fan  shut  off  when  you  turn the  ignition  off,  and  not start from  cold until  the  coolant reaches  operating temperature?

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.

 

[BlueBuck]

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)

 

[davefrombc]

What  I  was saying in the  last  paragraph is that  if  there  is a  hot wire to the  fan when  ignition  is  on or  off,   and the  temperature switch switches the  ground side  of the  fan  wires  then  a  spurious  ground would keep  it  running....From  what  you  say ,  once the  fan  is   turned on by the temperature  switch then  it stays  on  until  the  coolant  cools to the  point  the  switch  opens  whether  the  key is  on or not. It  sounds  odd to  me,  but that  may be the  way  it  is designed and there  is nothing wrong. I   have no  idea  if that  is the  way with   your  machine , but  I know  in   the  automotive world that  is the  way some  electric fans work  and also some  oil pumps  for  turbo  charger coolers.

My  reference to   "Fun"    was really  meant to refer to the frustration  that  is far too  common  trying to   trace  down  electrical  faults...  It  certainly  isn't  enjoyable .

 

Edited June 9, 2017 by davefrombc

[BlueBuck]

14 hours ago, davefrombc said:

What  I  was saying in the  last  paragraph is that  if  there  is a  hot wire to the  fan when  ignition  is  on or  off,   and the  temperature switch switches the  ground side  of the  fan  wires  then  a  spurious  ground would keep  it  running ( I believe the wiring is ok) ....From  what  you  say ,  once the  fan  is   turned on by the temperature  switch then  it stays  on  (NO MATTER WHAT UNTIL YOU PULL THE WIRES OFF THE TEMPERATURE SENSOR.) until  the  coolant  cools to the  point  the  switch  opens  whether  the  key is  on or not. It  sounds  odd to  me,  but that  may be the  way  it  is designed and there  is nothing wrong. I   have no  idea  if that  is the  way with   your  machine ( This is the way it is supposed to work with my machine but it doesn't), but  I know  in   the  automotive world that  is the  way some  electric fans work  and also some  oil pumps  for  turbo  charger coolers.

 

 

 

[davefrombc]

Something  you  could try  with  a cold engine.  Try jumping across the  temperature  sensor to  turn  on the fan   and see if  it   still stays  latched  on when  you  disconnect the  jumper..  Don't  disconnect the temperature switch, just  jumper across  it.

[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.

[davefrombc]

Then all  is working as it  should.. The fan won't  cut  off unless the engine cools below the temperature sensor switch turn  on   point and the switch opens..   You  could   just wire in  a switch to  disconnect  the  fan switch.  I wouldn't recommend it though. Kawasaki  had  a reason  to   set it  up that  way ,  and  if  you  wire  in  a switch to  disconnect  the fan  switch it is too easy   to  forget to  turn  it  back  on when you want to  run  the  quad  and end up  overheating  it. You  could wire in a  master disconnect  between the  battery  and the wire to the  ignition to  disconnect  all  power so  nothing  will  be  powered with it  off; but as   long  as your battery  is  good  it won't  hurt anything to  let the fan run  until the  engine cools to the point the fan switch  opens  and the fan turns off  on its  own... It easily  could take a half  hour  or  more  on  a hot  day.  but the fan  motor  shouldn't  draw a  lot  of  current and deplete  the  battery.

 I  would be inclined to just   wire  in  a  battery  disconnect.  Not  only does it  ensure  there  are  no  powered circuits when  it  is  opened,  but it  also  slows  down  a  thief  who  just tries to  hotwire the  ignition .  It won't stop   determined thieves  who  knows  to  look  for a  disconnect , but  it  does slow them   down  and could be  just the  delay  needed to  make them  look  elsewhere.

[BlueBuck]

16 hours ago, davefrombc said:

Thanks Dave. This certainly gives me some options. Thanks for hanging with me on this. Your a real value to this forum.