OMC Tachometer Cable Install Issue

[acolic]

Hi,

I have an OMC 3 cable with three wires (purple, black, and light Grey) which plugs into my remote control.

Using my multimeter I have identified that the black is ground and the light grey is positive.

With the motor on I get a bit more then 12V across the black and grey wire.

Here's the issue. If I attach the two wires (black and light grey) coming from the OMC control to my 12V gauge nothing happens.
If I attach a black and red jumper wire from the battery directly to the gauge it works correctly.

I can't figure out why my multimeter shows 12v across the two wires but once I attach them to the gauge nothing happens.

The 12v gauge is a Sierra-57901P.

https://www.amazon.com/Sierra-57901P-Voltmeter-Amega-8-18/dp/B000FQ1T5O/ref=ya_od_pd_dx_s_2?_encoding=UTF8&pd_rd_i=B000FQ1T5O&pd_rd_r=VD81WRVEDHEQQ2QJ2FQ1&pd_rd_w=eMq8h&pd_rd_wg=Q928m&psc=1&refRID=CWTDRZGH4HF4W9RZZZ95

Any suggestions?

Thanks

 

[DaleH]

While the Gray = signal (sender) & black = ground ... you missed the purple wire. Purple = switched + power (when ignition is ON), so you essentially had no 'power' to the tach, in the way you tried it.

 

[acolic]

While the Gray = signal (sender) & black = ground ... you missed the purple wire. Purple = switched + power (when ignition is ON), so you essentially had no 'power' to the tach, in the way you tried it.

Hi,

with the motor on if I use the multimeter on the black and purple wire I get zero volts.

Are you saying I should get a reading?

Because with the motor on I only get volts across the black and light grey.

Thanks

 

[DaleH]

You're just reading the 2 wires are 'talking' to each other, in that there's current/powerin THAT loop. But without the purple wire to the tach you haven't powered the tach. If you recall, if/when you turn an ignition switch ON, the needles move somewhat - indicating they are powered.

For the tach to work properly you need all 3 wires ... power (purple), signal (gray) and ground (black) ... connected.

See: https://www.jamestowndistributors.com/userportal/document.do?docId=837

 

[acolic]

Thanks I will try that.

Now if I wanted to use the three wires to also power up a voltmeter could that be done?


Sent from my iPhone using Tapatalk

 

[DaleH]

Now if I wanted to use the three wires to also power up a voltmeter could that be done?

No need for the gray, that is the tach signal. Keep in mind most newer fishfinder or GPS chartplotter combos have the capability to read the voltage for you.

For gauges, you daisy chain the purple "hot when ON" wire from gauge to gauge. Same with ground. Add blue switched wire if you want them to light up.