Johnson Tach inop

W

wroberts

Recruit
Joined
Aug 7, 2009
Messages
1
Have a '99 Johnson 70HP (J70PLEEE) that has a tach issue. Replaced reg/rec and have 0 volts on gray wire key on /engine off and 3.5 volts with engine at idle with no tach operation. Is this voltage running AC or DC at the gray wire? Boat runs great just no tach. Charging around 13.5 volts at 2000 rpm (guessing the rpm). Has 12 volts at tach purple wire and good ground.
 
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wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Johnson Tach inop

Purple is just a switched 12 VDC for internal illumination, grey is pulses to tach, black is ground. Check the grey at the engine end ... wire may be broken or have a poor termination or shorted somewhere.
 
countvlad

countvlad

Chief Petty Officer
Joined
Jun 29, 2009
Messages
439
Re: Johnson Tach inop

wroberts said:
Have a '99 Johnson 70HP (J70PLEEE) that has a tach issue. Replaced reg/rec and have 0 volts on gray wire key on /engine off and 3.5 volts with engine at idle with no tach operation. Could another circuit be pulling this voltage down? I believe it also runs to the VRO unit. Boat runs great just no tach. Charging around 13.5 volts at 2000 rpm (guessing the rpm). Has 12 volts at tach puple wire and good ground.
Click to expand...

try this...

for a water cooled rectifier:
http://forums.iboats.com/showthread.php?t=190636

or a small 3 wire rectifier"

http://forums.iboats.com/showthread.php?t=190638

its very possible you have a bad the tach .... 3.5V at idle sounds about right..
 
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