Four wheel drive not working 2004 450 ES

[NB Floyd 35]

Went riding yesterday. 
 

Pretty quickly I found out that four wheel drive was not engaging.  
 

4x4 light came on.  ( and off when switched to 2wd)

 

No unusual noises.   The electrical connector felt tight at the top of the front diff. 
 

Any thing to check for ? Any common issues?

 

thanks

 

NB Floyd 

 

2004 450 ES

[AKATV 822]

Usually with your model (02 and up with selectable 2WD/4WD) ,if there is a 4x4 fault, the 4WD light will flash a few times as a code, indicating a fault area

usually, it  flashes 2 to 6 times

Is it flashing at all?

Edited April 14 by AKATV

[shadetree 5,869]

most times when this happens, one of the speed sensors goes bad on the front diff. there are two of them on the front diff, one is right where the front drive shaft enters the front diff, and the other is located in the front, top side of the diff. if this is not the issue ?, then the 4wd unit ( control unit ) is bad.

[NB Floyd 35]

Took a quick look at the bike this morning. 
 

The 4x4 light did not flash with engine off and key on.  Did not try with it running.  
 

I saw the speed sensor on top of the diff , and a elec connection at the drive shaft input. 
 

The wire at the drive shaft input was pulled out of place and under strain , I routed it back under the shield.   Hopefully that helps. 
 

is there a 4x4 actuator in / on the front diff , is that what the 4x4 switch controls ?

 

thanks !

 

NBF

[spock 42]

First thing I'd do is check the condition of the splines on the front prop shaft - the ones near the front of the engine can get stripped, common problem on those older Honda's.

[jeepwm69 7,611]

Yep, if throwing no blinking codes I'd check the spines on front driveshaft and coupler.   I've had to replace a few.

[shadetree 5,869]

On 4/15/2024 at 9:43 AM, NB Floyd said:

Took a quick look at the bike this morning. 
 

The 4x4 light did not flash with engine off and key on.  Did not try with it running.  
 

I saw the speed sensor on top of the diff , and a elec connection at the drive shaft input. 
 

The wire at the drive shaft input was pulled out of place and under strain , I routed it back under the shield.   Hopefully that helps. 
 

is there a 4x4 actuator in / on the front diff , is that what the 4x4 switch controls ?

 

thanks !

 

NBF

yes, the sensor where you adjusted the connection, that is where the speed sensor is. as stated, be sure to check the pinion collar splines for being stripped ?.

[NB Floyd 35]

I put the bike on a stand to check 4x4. 
 

it seems like the propellor shaft has stripped splines at the motor.   
 

when 4x4 switch is activated the out put shaft turns but front wheels do not engage. 
 

I could actually hold the shaft still and hear a noise in the coupling at the front of the motor.  
 

good news is that the front diff spins the shaft with no slip when I turn the wheels by hand in 4x4. 
 

what is the replacement propeller shaft called ?

 

 

I understand you need to unbolt the front diff to move it forward.  Are there any fasteners on the propeller shaft ?   Any other tips to make this a smooth replacement?
 

Thank you.  
 

Nbf.  

[jeepwm69 7,611]

You'll undo a bolt on the bottom of the front diff (14MM), a bolt and spacer on top of the diff (I think 14mm on nut/bolt) and the mount on the front of the diff.   I remove the metal bracket on the front, or at least unbolt it, and loosen the bolt so you can swivel it out of the way.

 

That's it.   Pull the front diff forward.   The prop shaft will then just slide out. 

 

Check and see if you need the prop shaft or the coupler, or both.  Also check the splines on the shaft coming out of the engine.  They should be square cut, not pointed.   If they're pointed (shark toothed) they're worn out.

 

Used Shaft

https://www.ebay.com/itm/296213716938?epid=1911839859&itmmeta=01HVRVTQP5BSREC4RFXBMWHXNG&hash=item44f7b69fca%3Ag%3AA7MAAOSw9cRlxUff&itmprp=enc%3AAQAJAAAA8HJls4L8zrcD5BV69nyIFrpoNL4tguslMY9%2FXJBfvkAgiUjPZtgcCS%2ForBApuqsc%2FBFlBlCf0pzHMTAwMcoEBj6n3PkpDrg%2Fca9DB%2FOJ--3eGB%2Bz%2FdoDysjhrTzXWjxX2GfX%2BkoNj5r9WQQewOnV29CxZL%2FG7Z2vL%2FcYHWyb69QzRsULM4aqgwzJwzPzmkYmssvVhrXztzrjyXZv%2B3mXpBLWHUEw7yTLEUQL1CKBVh7ipWluy5w95VCYdFWCFxVV0I2HRA2X%2F2ZAeetS29FF48w0wyPQd0KAvW%2FqwHN0wQXOXukFt7B9UspDeyg%2BwZWpSQ%3D%3D|tkp%3ABk9SR5L76pveYw&LH_ItemCondition=4

 

Used Coupler

https://www.powersportsnation.com/honda-rubicon-500-fa-02-front-drive-shaft-engine-coupler-40402-hn2-000-44196.html

 

If you want new, part number for complete shaft and coupler is 40400-HN0-670 and it's about $200. 

 

https://www.motosport.com/oem-parts/part-number/40400-HN0-670?mmy=honda%3Btrx450 foreman 4x4 es%3B2004&group=front-final-gear&qty=1

 

Those are the cheapest used parts I could find, and the cheapest new shaft I could find.   Note that you need 02-04 only.  The earlier 450's were full time 4wd so the shaft is different.