I have a 2004 trx 400 that has developed an annoying issue with the hondamatic. With the service manual i've managed to narrow it down to either the angle sensor or the ECM, but i don't know which to try first.
What happens is every time i start the bike it runs fine then if i put it in D or R it will say D or R for a few seconds then it will turn to flashing "--". Sometimes in D if i take off really fast it will work normally but once i stop again it will flash "--". Whenever the "--" is flashing it will only drive like it is in first gear. When I put it in reverse regardless of how fast I do it the machine will bog and hardly move as if the rpm's are being limited.
I have taken the angle sensor off and it was clean and moving freely and put it back on (preloaded) and still the same. I have also tried the initiating procedure but on the first step (UP, DOWN, UP with throttle motion) I can hear the control motor moving like normal but afterwards the screen continues to flash "--" when it is supposed to be a solid "N". In the service manual it says to make sure a solid "N" is there but doesn't say what to do if it's not there!

Also, the angle sensor was replaced just a few months ago. I did the code reading this time and got 5-angle sensor (motor lock). I know the angle sensor only costs ~$70, does anyone know what the ECM costs?

Thanks

 

Remove the left side cover where your foot goes, there a 3 ele. connections one labled f one labled r one not labled ... the one not labled is closest to the outside, clean and make sure this connection is tight,
Keep us posted

 

I check all three of those connections, all were clean but cleaned them anyway and no luck. I have a new ecm ordered and hoping that it fixes the issue.

 

Hi I'm also having the exact same problem with my trx400fa 2005 model I have tried to reset it and have tested the wiring and the sensor and I even pulled the harness out and inspected it any ideas ??

 

The angle sensor will need to be replaced, I've had it happen 3 times to mine. The angle sensor seems to be a common failure in these machines. And from what I have learned, it has to do with the angle sensor wiring getting wet, possibly shorting out. The last time I replaced the angle sensor I added a fair amount of dielectric grease to the connection, this keeps the water away from it and keeps the wires dry. I haven't had to replace it in over 3 years now, knock on wood!
You can get the sensor online from somewhere, it's not very hard to install yourself, just be sure you preload the spring before reinstalling it.

 

No worries thanks it's funny though I only put a set of rings in it and since I have had it apart I have had this problem no worries thank you for your help