tach not working

Andy in NY

Andy in NY

Commander
Joined
Oct 25, 2007
Messages
2,109
1970 evinrude 85 hp

tach is an outboard tach set to pole 1 (4cyl)

have pos and neg running right from battery, and grey wire from inside controller to sig on tach, but get no reading what so ever. where do i start troubleshooting?
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: tach not working

try the "6p" setting.

Does the tach peg zero when connected to battery? If not, confirm voltage on your wiring (to rule out wiring fault), then replace the tach.

Is the outboard charging circuit working? If not, the rectifier is faulty (tach signal comes from rectifier).

Can you read any AC voltage on the gray wire with the engine running? If not, look for open circuit fault on the gray wire. Otherwise replace tach.
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,762
Re: tach not working

The tach sense lead comes from the charging system and not the ignition system so it not # of cylinders dependant. The charging system outputs 6 pulses/engine rev so as suggested, try that setting.
 
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