2003 Johnson 150hp outboard - tach gauge issue

Rincon823

Recruit
Joined
Feb 2, 2015
Messages
5
Hi;

I have a 150hp Johnson outboard from 2003 and suddenly its tachometer stopped working. A mechanic told me that voltage rectifier/regulator should be the problem. So I replaced it with a new one but issue persist. Tachometer was not working. I also replace the gauge with a new one... same results. :blue:. Current gauge include the tachometer and also the check engine system lights (hot, no oil, etc...)

Any idea of what could be the problem?

Any suggestion is appreciate.
 

Rincon823

Recruit
Joined
Feb 2, 2015
Messages
5
Yes, there is power. When I turn the key in the ignition, gauge perform some type of a self test. All check engine lights blink and alarm sound (it takes like 2-3 seconds).
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Have you checked for continuity to the gauge from the tach wires on the engine, ie make sure it isnt broken somewhere
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Check the boat wiring harness where it enters the engine. I had a melt down there, shorting the tach wire. Also check for melting under the dashboard.
 

Rincon823

Recruit
Joined
Feb 2, 2015
Messages
5
Thanks for feedback... I'll check that. Just a note: wiring harness is new. It was replaced few months ago.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
One one of my older engines, I had the same problem. Decided to run a new tach wire from the engine up to the tach on the dash. Was an "open" in the grey wire somewhere in the control box harness or main engine harness. Was easier to run a new wire. You could run a temporary 15' wire just for testing-then decide if you want to actually string in up on a permanent basis-under the deck..
 

Rincon823

Recruit
Joined
Feb 2, 2015
Messages
5
Correct, wiring harness was replaced because it was melted. Motor overheated about a year ago.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Well, I had my wiring harness melt, due to an electrical short. Never found the problem, and it happened before I bought the boat/motor.
 
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