2006 rancher AT temp sensor

[beer 8]

Hi Guys,

2006 Rancher AT with a temp sensor issue. When I purchased the ATV it would run really hot, but the temp light never came on. The cooling fan never turned on either.  I purchased a new Honda OEM temp sensor and installed it. Fan will still not come on and the ATV still gets hot.  I grounded the sensor wire to the engine block to check if fan was good and the fan works fine. For the mean time I just grounded the fan so if the key is on, the cooling fan is on. That works, but with doing that now the temp light is on constantly. I would really this to work as it's supposed to but I'm stumped at this point.

 

Anyone have any suggestions as to where I can go next with it?

 

Thank you,

Jeff

Edited June 9, 2022 by beer
Screwed up

[shadetree 5,977]

i don't think those models have a fan control unit ?, i believe they work out of the ecu if i'm not mistaken ?. where did you buy the temp sensor ?..amazon ?, ebay ?, got to be careful buying parts from these places..they love to sell parts claiming its oem..when in fact..its china !.

[beer 8]

The ATV has a temp sensor low in the rear of the block. Part number 37750-HC4-751. I did buy it from eBay. It came in a plastic bag with all the correct Honda markings on it. That's all I know. The sensor is oil temp as the ATV is air cooled.

Edited June 9, 2022 by beer
just cause

[ATC4ever 1,090]

How dirty was the machine? Like, under the 'hood' so to say? Sounds like a connector issue, dirty more than likely.

[jeepwm69 7,751]

16 hours ago, beer said:

The ATV has a temp sensor low in the rear of the block. Part number 37750-HC4-751. I did buy it from eBay. It came in a plastic bag with all the correct Honda markings on it. That's all I know. The sensor is oil temp as the ATV is air cooled.

 

 

If the fan and temp light come on with the wire grounded, it usually points to a bad sensor.  While getting a new one out of the box that is bad would be rare, it could happen.

 

Look in the factory service manual page 22-13 for troubleshooting instructions on wires, sensor etc.

[beer 8]

What is the temperature the sensor is supposed to operate at to turn on the fan? I'm thinking I can test it by grounding it and hitting the probe end with a heat gun..

If I run a hot wire to the sensor and a ground wire with a test light I should be able check both the new sensor and the old one off the machine correct?

Edited June 11, 2022 by beer

[Goober 1,555]

The fan should come on about 100C; 212F.

on my older quad, the oil overheating diagnostics explains this way: 

You can test the temp sensor by using an oil bath with an instant read thermometer and ohmmeter. You’re try to validate that the sensor reaches 1.05ohms to 0.95 ohm at 100C.

 

Mine sensor reaches 0.95ohm between 200F-220F depending on whether it’s a slow climb or fast climb on heating the oil. 

if you have a hard oil light my bet it’s not the temp sensor but the fan controller.

 

edit i corrected to indicate you’re testing the temp sensor not the fan.

Edited June 11, 2022 by Goober

[Fishfiles 20,147]

3 minutes ago, Goober said:

The fan should come on about 100C; 212F.

on my older quad, the oil overheating diagnostics explains this way: 

You can test by using an oil bath with an instant read thermometer and ohmmeter. You’re try to validate that the sensor reaches 1.05ohms to 0.95 ohm at 100C.

 

Mine comes on between 200F-220F depending on whether it’s a slow climb or fast climb on heating the oil. 

if you have a hard oil light my bet it’s not the temp sensor but the fan controller.

Dang Goob' , pretty high tech looking rig up , Mad Scientist  !!! 

 

 

 I was working in my lab late one night , 

when my eyes beheld an eerie sight , 

 suddenly  , to my surprise ,

the temperature began to rise 

 

 

 

[beer 8]

Thank you for all the help guys!  Boy is my wife going to be mad when I start heating motor oil on her stove..... Might need a divorce lawyer after this test but hey, at least the quad will be fixed.

[Goober 1,555]

You can get an electric hot plate pretty cheaply compared to the indoor option.a flame heater just heats too quickly you want slowest rise possible 

 

cheap canola smoking point pretty high. You will need a meter that reads KOhms and ohms. I made a mistake earlier by not properly indicating 1.05 - 0.95 K ohms!!!

Manual should explain what your sensor resistance value should be at cold engine (77F). Typically Honda 10.5K ohms

at ~212F, your fan should come on but not the oil light. 1.05-0.95 Kohms

at ~322F your oil hot light should come on. ~260ohms is essentially zero resistance.
 

Then fry some fish.

Edited June 11, 2022 by Goober

[beer 8]

You mentioned the fan controller earlier.  Are you referring to Part# 35250-HN4-670.  Sorry for all the questions. Just trying to understand how the whole system works.

[Goober 1,555]

My quad has a fan controller—yours may/may not. Use the oil cooling system diagnostics section in your service manual to  target the correct module(s).

[Goober 1,555]

3 hours ago, Fishfiles said:

Dang Goob' , pretty high tech looking rig up , Mad Scientist  !!! 

 

 

 I was working in my lab late one night , 

when my eyes beheld an eerie sight , 

 suddenly  , to my surprise ,

the temperature began to rise 

 

 

 

Lol not a mad scientist like Gene Wilder, more like Marty Feldman!

[wheelsquad 108]

This exact problem is why I love my @retrofan control gizmo. I'm still amazed at how well it works every time I get on my Rancher AT. 

[jeepwm69 7,751]

5 hours ago, wheelsquad said:

This exact problem is why I love my @retrofan control gizmo. I'm still amazed at how well it works every time I get on my Rancher AT. 

 

Welcome back wheelsquad!  Glad your Rancher is still running strong.

[wheelsquad 108]

16 hours ago, jeepwm69 said:

 

Welcome back wheelsquad!  Glad your Rancher is still running strong.

Thanks! Yep still kinda surprised she’s hanging in there. Might be due for a 2nd clutch replacement soon though.