Ask The Editors: What Is a Motor Control Unit?
Yes it’s real. No it isn’t the same as the CDI.
Good eye! For years we’ve erroneously heard that the terms MCU and CDI were interchangeable but you are indeed correct, the Motor Control Unit is a separate component found on most of Yamaha’s line.
So what is it if the machine already has a CDI box and a voltage regulator? The Motor Control Unit is a similar electrical control box responsible for distributing current only this one pertains specifically to the machine’s fan motor.
While it is technically possible for the unit to fail, it’s very unlikely responsible for any gremlins you’re trying to diagnose as even a complete failure results only in a radiator fan that won’t kick on regardless of engine temp.
However, like any electrical snafus, be sure to check these circuits with a meter for direct shorts in your investigation.
