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Need help diag cooling system

4560 Views 22 Replies 8 Participants Last post by  gentrydeg
I was riding this afternoon and out of the blue over heat light came on. I noticed the fan was'nt runing. I have a 06 700 xp with 307hours. Made it home and looked it over. It never boiled over, but did feel the over flow. I unhooked the fan harness and put staight to battery and fan runs. I have a 07 manual and it says to set the parking brake turn on the ignition key and unplug the sending unit and the fan should run if the fan is ok. The fan did not run, but i know it is good due to going to the battery. I dont think the testing is the same on the 07 model. Please help with problem. Dewayne.
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check fan relay under hood, you should have two of them side by side, one is the fan and the other is the starter (swap them around, if fan works then the starter will not, and you have a bad relay) . next check to see if you have 12 volts going to the fan, if above is good check ground.
Does the 06 have relays, i hav'nt seen them i will look. I do have 12 volts going to the fan. I'll check the ground. Like i said earlier, the fan will run if go straight to the battery. How do you test the sending unit. Dewayne.
I still need help. Does anyone have a 06 manual with the test procedure. I have a 07 manual and having no luck. I have 12 plus volts going to the fan but when i plug it back up it kills the voltage. I can run a hot and a ground from the battery and the fan will run. I did notice a spark when i touched the wires to the plug but asumed it was the fan kicking on. Thanks Dewayne.
I know someone is out there. Help! Dewayne.
I guess i need to move this post to the rzr forum, i think that is were every one is hanging out. I know someone has a 06 shop manual that can help. Dewayne.
Email hiatt65 I know he has a manual.
Thanks Curt for the reply. Dewayne.
I still need help, but i just emailed haitt65. I'm posting so this subject does'nt die. Dewayne.
I will check my manual first chance I can, I am at work.
I have my Sportsman 800 manual with me on cd. It says fan may not come on if coolant is low or has air in it. It also says to check the coolant temp sensor and connector terminals. I would put lithium grease on all conectors, that might fix it. If the coolant temp sensor malfunctions the radiator fan will default to "ON".
I will check my Ranger manual when I get home.
Thanks smitty your help will be appreciated. I'm hoping the problems is not in the ecm. Dewayne.
My Ranger manual says about the same thing as my 800. It tells how to check the coolant temp sensor but if it was bad then the fan should run all of the time. I will tell how to check it just in case you want to know.
Disconnect the harness connector, check the resistance on the sensor contacts. With the engine cold the resistance should be 2.5 k ohms or 2500 ohms.
Sorry I couldn't be more help.
Thanks smitty i will check it. I'm affraid it's going to be my ecu. Dewayne.
Looks like the ecm module under the hood is bad, i will know for sure thursday. Dewayne.
Took a ride around the property a couple weeks back and the overheat light came on. Noticed that the fan wasn't running.Had the same problem in June 07 and had to replace the ECM under the hood to repair.

After a few short test it was determined the ECM was the culprit. Sure enoungh $260 later the fan is back working.

Is any one else having this problem? The local dealer had the part in stock which tells me they are selling them.

No accessories added to the electrical system to be shorting out the ECM...

What do you think?
I've seen posts of it happening to a few '06 models. Not a widespread problem, but enough that they changed to a different ECM in '07. It happened to mine back in the summer. I replaced it and haven't had any issues since then. Suposedly, from what I was told by the people that make the rectifiers for it (I tried replacing the burnt rectifier first), they changed to an improved rectifier and the problem shouldn't happen on ECM's made after early '07. So if you've recently bought a new ECM, chances are that it was made after that date and should last longer......theoretically.
I hope it does. I have 570 hours on the Ranger now. I really enjoy it but was about to jump ship.

I went and test rode a 08 Teryx and a 09 Rhino. Just wasn't a Ranger...
Have you checked the ground for the fan? If you are adding direct voltage to the fan and it runs, does that mean you are supplying ground as well. If you have 12 volts to the fan when everything is hooked up properly and the fan doesnt run, but does when you hot wire it. I would look closely at the ground and take it off, clean and coat it with dielectric grease. Power means nothing when you dont have a ground. hope this helps
I have run a direct ground to the ECM. Will look at the fan ground as you have described....
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