Do I need a tach control unit on a Suzuki.

Daveparm

Petty Officer 2nd Class
Joined
Sep 13, 2014
Messages
122
I created an earlier post that was probably overly complicated. I was wondering if a tach control unit is necessary on a 1986 DT115 with Suzuki tachometer. It appears mine is bad and my tach. will work if I bypass it. I just don't want to damage anything else (ecu, rectifiers, exec.) I would love to get on the water tomorrow, but if I can't find out what this thing does and if it is needed, I'll cautiously wait. Thanks much
 

chackett

Seaman
Joined
Mar 1, 2012
Messages
52
This is a good question, and I would be interested to know what you find out. I have another thread here where I'm running down a problem with my tach / electrical system. My main symptom is that my tach is reading about 2x the actual RPM. I've gotten lots of advice (none of it from here though) and one person suggested it might be the tachometer control unit. My problem is slightly different in that I don't really care what the tachometer is reading .. I've used a handheld tach to verify the actual RPM .. but I think maybe the tach control unit is causing my rev-limiter to kick in, falsely believing my motor is turning a LOT faster than it is.

I don't know what exactly the tachometer control box does, but It's on my list of things to replace if a new rectifier / voltage regulator and gear counting coil don't fix my problem.

Keep us posted.
 

Daveparm

Petty Officer 2nd Class
Joined
Sep 13, 2014
Messages
122
I hope you figure out what your issue is as well. Being that I didn't get much response on this I did roll the dice and went out without the control unit. The tach reads fine at idle yet wouldn't register above 2000RPM, even know I was turning much faster. When I ran with it the tach would sometimes wor and sometimes not. When it did work it never would read above 4,000 rpm. I plan to order a used one and just try it as I'm not sure how to test it. (no info in the manual). There appears to be a diode involved as I get continuity in one direction.
 

chackett

Seaman
Joined
Mar 1, 2012
Messages
52
Thanks for the reply Dave,

I don't know if the tachometer control unit is my problem, but I've replaced a lot of other things (rectifier / voltage regulator, gear counting coil, etc) .. and the tach control unit is about the last thing for me to check. My problem seems to be somewhat the opposite, in that my gauge is reading much higher than the motor is turning, and eventually the rev limiter kicks in, even though the motor isn't turning nearly high enough for it to be necessary.

I only mention that to suggest that if indeed the tachometer control unit plays any part in activating the rev limiter, you might just be aware that the protection provided by the rev limiter may not be available without the tachometer control unit. I think most people will know when their motor is in the danger zone, but might just be worth mentioning.

Good luck!
Chris
 
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