'99 Johnson 90hp - Tach Frozen

mgb

Cadet
Joined
May 13, 2009
Messages
8
Hey all.

Out for the first run of the season yesterday. Everything worked well as it always has. That is, until I realized the tach was frozen at about 500 rpm. It does NOT hit absolute zero. It does not seem to move at all at key on, start, etc. I just replaced the battery this spring. Had no problem with the tach prior to the battery repacement. Seems to be charging fine...voltimeter showing 14+ at higher rpms, so I'm hoping it's not the rectifier.

Since the tach is not hitting absolute zero and I just replaced the battery I'm wondering if it could be a wiring/ground issue? When I replaced the battery, I first connected the pos and neg to their terminals, the two accessory pos and neg connections next (on their respective terminals) and then the nuts on top. Should I have put the accessory connections on first and then the pos and neg cables followed by the nuts?

The warning lights and beep on the tach come on at start but I'm concerned that they might not be actually working and would not provide warning in the event of overheating, low oil, etc.

Anyone have any thoughts on this? Thanks for any help!
 

mgb

Cadet
Joined
May 13, 2009
Messages
8
Re: '99 Johnson 90hp - Tach Frozen

bumping in hopes of some insight...
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,122
Re: '99 Johnson 90hp - Tach Frozen

The tach uses ground, +12VDC and the signal from the voltage regulator. Depending on the brand, it should zero with key on and motor not running. Check the connections to the tach to make sure it gets ground and +12VDC. Next do a continuity check on the grey wire from the voltage regulator thatthe tach. It should have zero resistance.
 
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