Using Old Style Round MFD Tach w/ 4 Stroke

[Jason2tpa]

From what Ive read, 4 strokes monitor oil pressure and do not monitor oil level. The newer style tach incorporates a oil pressure alarm symbol. Can the older round multifunction digital tach be configured to monitor oil pressure, as well as the ability to activate the oil pressure alarm, when paired with a F115? The 703 control is being used.

[rodbolt17]

could I wire it?
yep all but the trim function.
look at the back of the tach. if it has a rubber plug with 3 dip switches it is a compatrible tach.

the digital multi functions did NOT measure oil pressure.

remember it all works on ground paths.
the old two stroke tach if you ground the green oil lead the far right bar lit. remove the ground and the and the center bar or light lit/flashed.
ground the green red and the far left lit.

can it be jury rigged? yep.

[Jason2tpa]

could I wire it?
yep all but the trim function.
look at the back of the tach. if it has a rubber plug with 3 dip switches it is a compatrible tach.

the digital multi functions did NOT measure oil pressure.

remember it all works on ground paths.
the old two stroke tach if you ground the green oil lead the far right bar lit. remove the ground and the and the center bar or light lit/flashed.
ground the green red and the far left lit.

can it be jury rigged? yep.

So lets say the tach does have the dip switch. Of the 3 solid bars, which one will blink to indicate low oil pressure? And will rpm reduction mode activate when the signal is received?

[fairdeal]

And will rpm reduction mode activate when the signal is received?

the tach itself doesn't do anything except present a powered lamp for the engine ECM to illuminate by grounding it.

in the event the ECM sees low oil pressure from the switch on the engine, it will reduce rpms - and sound the keyswitch horn - whether or not there is a tach connected.

[Jason2tpa]

the tach itself doesn't do anything except present a powered lamp for the engine ECM to illuminate by grounding it.

in the event the ECM sees low oil pressure from the switch on the engine, it will reduce rpms - and sound the keyswitch horn - whether or not there is a tach connected.

Gotcha, thanks. Still curious about the visual indicator the tach will show when low oil pressure is detected.

[rodbolt17]

if you have a tach with 3 dip switchs and they are correctly set then low oil pressure visual is the far left bar blinking.

if you jury rig an older tach it will be 3 bars flashing.

[boscoe99]

Newer style multi-function tachometers are adjustable so they can be set for a four stroke model or a two stroke model.

When set to the four stroke mode normally there will be no bar displayed above the oil pot symbol. If and when low oil pressure is observed by the ECU the bar will illuminate and blink. As fairdeal notes, the engine will sound the alarm and put the motor into RPM reduction mode but this has nothing to do with the tachometer itself.

When set to the two stroke mode normally there will be three bars displayed above the oil pot symbol. If and when there is low oil quantity in the remote tank the right hand bar will disappear and the middle bar will blink. If and when the main oil tank runs low the middle bar disappears and the left hand bar will start blinking. The engine will sound the alarm and put the motor into RPM reduction mode independent of the tachometer.

If you have an older tachometer that cannot be set to a four stroke mode then yes, you can wire it so that the left hand bar will blink if and when there is low oil pressure in an F115. You would simply wire the low oil pressure ground lead from the motor to the low oil quantity lead on the tachometer. Now if the tachometer has lights then the same applies. Wire the engine low oil pressure ground lead to the lead that will illuminate the red low oil quantity light.

[boscoe99]

How about posting a photo of the front and back of the tachometer in question.

[Jason2tpa]

How about posting a photo of the front and back of the tachometer in question.

Not my tach or engine. Helping out someone.

[boscoe99]

Not my tach or engine. Helping out someone.

And he does not have a camera?

[rodbolt17]

if you jury rig the old style tach with 2 or no dip switchs you have two choices.
the middle bar always is on and the far left bar will go on if oil pressure is low .
or you can get 3 bars flashing if oil pressure is low.

[Jason2tpa]

And he does not have a camera?

Possibly. I told him to first check the back to verify the tach does or does not have the rubber grommet that acceses dip switches

[Jason2tpa]

if you jury rig the old style tach with 2 or no dip switchs you have two choices.
the middle bar always is on and the far left bar will go on if oil pressure is low .
or you can get 3 bars flashing if oil pressure is low.

Good to know thx