# Yamaha 4wd Testing Procedures Step by Step with Videos



## oleblue22 (Sep 17, 2012)

*Yamaha 4wd Testing Procedures*
I’ve included links to videos and parts. To see clips of the *service manual* pertaining to these tests look here. 501parts.com - Downloads
These are the most common problems that happen. If there is something else you’d like to see just let me know. 
*Problem 1*—4wd won’t work at all, and does nothing when the button is pressed.
*Step 1*- Check the fuse
*Step 2*- Tap on the relays, one could be stuck (Two black with G8HN# on top and one white relay on most models.) Also check the connections on the servo and relays to make sure they’re connected properly.
*Step 3*- Remove the front diff servo and proceed to test it (need two c batteries, T-45 tamper proof torx, and a 6 mm allen. Some use 10mm regular hex bolts) see video Testing the three servo types - YouTube
If it tests bad, you can find a replacement motor here. 501Parts.com - Yamaha Servo Motors
If you need the bits to remove it from the front diff you can find them at any parts store or you can order them here. 501Parts.com - Yamaha Servo Motors 
If it tests good, proceed to next step. 
*Step 4*- Test the three relays. You’ll need a multi-meter set on the lowest ohms setting usually 200, and a short run of wire to power up the relays. See video Testing the three 4wd relays on Yamaha ATV's - YouTube
If they test bad, you can find a replacement here.
501Parts.com - Yamaha Servo Motors
If they test good, proceed to the next step.
*Step 5*- Test the push button switch (you’ll need a multi-meter set to ohms) see videos
Testing 4wd Switch Yamaha ATV's/SxS's version 2 - YouTube 
Testing the Push Button 4wd Switch on Yamaha ATV's - YouTube 
For a switch that tests bad, you could try cleaning it before buying one. See video. Cleaning the Yamaha 4wd push Button Switch - YouTube 
If it tests bad after cleaning or you just want a new one, you can find it here. 501Parts.com - Yamaha Servo Motors
If it tests good, proceed to the next step. 
*Step 6*- At this point you are certain your servo, relays, and switch are good. Next, you’ll want to start tracing wires looking for anything that’s frayed or broken. Common places for problems are under the fusebox on SxS’s, under the front racks on the ATV’s. Also check the connections under the relays beneath the seat on the ATV’s. You may have to untape and untie your wires to get to the problem. 
If you’ve tried all of this and still can’t get it going, you are welcome to call me at 501-658-0219 and I’ll help you through it. 

*Problem 2*—I have replaced my servo motor or cleaned my servo assembly but now I’ve gotten it out of time and it’s not working properly. 
*Step 1*- First you want to make sure not to bolt it up before you know certain it’s working. You should have the slide gear inside the diff to the left if you’re sitting on or in the seat (or to the front of the bike for those that go back and forth instead of left and right), have button in 4wd and the servo should be timed to 2wd. 
See these videos for cleaning and retiming. 
Cleaning and Retiming Yamaha 3B4 Servo - YouTube
Cleaning and Retiming Yamaha 5KM servo motor - YouTube 

*Problem 3*—My ATV or SXS goes into 4wd or diff lock but will not come back out. 
*Step 1*- Try tapping on or swapping your two black relays and see what happens (if something changes then one is bad) proceed to test the relays to determine which one. You will break the clips off removing them. Almost no way around it.
See video Testing the three 4wd relays on Yamaha ATV's - YouTube
For a replacement 501Parts.com - Yamaha Servo Motors 

*Problem 4*—My relays just click when I try and go in 4wd but I don’t hear the servo working. 
*Step 1*- Ensure the connection on the servo is tight and connected properly. If it is proceed to next step.
*Step 2*- Remove the front diff servo and proceed to test it (need two c batteries, T-45 tamper proof torx, and a 6 mm allen. Some use 10mm regular hex bolts) see video Testing the three servo types - YouTube
If it tests bad, you can find a replacement motor here. 501Parts.com - Yamaha Servo Motors
If you need the bits to remove it from the front diff you can find them at any parts store or you can order them here. 501Parts.com - Yamaha Servo Motors 
While you are inside the diff, ensure the slide gear can be moved back and forth with your finger with ease. You may have to roll it a little to get it to move but should move freely. If it does not move freely, you can remove the allen screw cap and then remove the slide rod and gear with an allen wrench. The gear, rod and fork will come out. You can clean the slide rod up with emery cloth or light grit sandpaper.
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