2012 Massimo Msu 5oo won't shift into 4 wheel drive?

[Jim Sabin]

I have a 2012 MSU 500 that recently was having an issue with the motor not starting,  I ended up reworking the ground wire at the fuel pump leads and now I have notice that when I switch to 4Wheel drive, it does not work. Any ideals what going on?

[Joe Breaux]

maybe you popped a fuse during  your other  wiring repairs .. Does yours have the dash indicator that shows which wheels are engaged?  

[cliffyk]

The MSU500 uses the same front differential as the MSU400, the Hisun HS400/500, the Bennche BH400/500, and the Coleman Outfitter 400/500. (see diagram below):

It is part #17, the Servo Motor, that engage/disengages 4WD and the differential locker. It is activated by the push button switches on the dash panel powered by a 3 or 5 A fuse in the fuse block. It would seem one of those components is not functioning properly.

 

Here is the procedure for checking the servo motor--NOTE that two 1.5 V batteries are used--do NOT use more than 5 V to test the servo.

 

[Dr Mark]

6/27/21

Thank you to whom posted the gear motor drawings. I have a 2019 Coleman Outfitter 550x with only 44 miles. Never driven off road. The 4wd will not engage and I pulled the gear motor as described from the drawings and used 2 C batteries and

the motor pinion gear worked as it should. Putting it back on the front axle it still will not work. When I pulled the electrical plugs from the gear motor I noted the dash 2wd/4wd indicator chgd to flashing "x"s on the front diffs. Otherwise,

when plugged back into the gear motor the front diffs do not change when pressing the switch for 4wd or the front locker. The switches seem to have power but Im at a loss. Anyone have any ideas???     Mark

[Ben1098]

You have more tests to perform:

1.  Raise all 4 wheels......jackstands.

2.  Remove the servo gear motor assy from the front diff.  Leave connectors on.  KEY ON   Have assistant cycle the buttons on the dash.  The pinion gear should should have 3 distinct stops....2WD, "3WD", 4WD.  If this works ok....check the diff rack function.

3.  The servo motor pinion gear (the 3 stops) drives the rack back and forth for 3 stops.  You are going supply the Left to Right to Left motion to the rack "block".  Have assistant rotate wheels as you slide the rack thru the 3 positions to get the 2, 3, 4WD diff functions.  If diff functions correctly, slide the rack to center position (usually the correctly timed position is off center by 1 to 2 teeth).  Then, select 3WD on the buttons (center).......insert slowly to engage the pinon to the rack.  Test button/wheel rotation combinations.  Adjust rack position to fine tune if required.

NEVER SHIFT INTO 4WD UNDER POWER/LOAD.  That will break the little rack pin or shift fork.

ALSO.....NO 4WD ON PAVED SURFACE WITH TURNING.  BINDS UP THE DRIVE TRAIN.  

CHOW

[unhappy]

I have   a t=boss with 4wd problems replacing the servo motor corrects this problem every time . I'm now going to install the 5th  servo at approx $250 .00 each. if some body can suggest a fix to what is causing the problem. Otherwise i'm buying a can of gas and a box of matches then i'm going and buy a real sxs. I wouldn't pass this thing to my worst enemy'

[Joe Breaux]

not really sure if its applicable here but I have found that 99% of my MSU 500 parts  that fail..[ and there has been many]  are interchangeable with  genuine YAMAHA RHINO parts.. and the quality is leaps and bounds better ... 

[Ben1098]

Do tests on diff for the 3 positions of the rack block L to R.

Do tests on servo motor by switching the dash buttons and watch the pinion gear....should have 3 stops to match the diff rack.

[Brent]

Just bought an Axis 500 and 4wd and differential  completely locked and won’t disengage. Jacked the front and moved the wheels by hand but no success.  Found a service manual at manualib.com but almost useless. Electrical diagram designations don’t coincide with actual components and wire colors are off.  Are the 4wd relays on the same board as the fuses? How do you test them? Can’t remove the servo connector to check it either.