Looking for the right tach harness from controls to tach?

Mtcowboyblue

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Oct 15, 2021
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Hello there iboaters! Quick question. I have a 2005 merc 115 efi fuel injected its the EXLPT. I put it on a 1976 ss StarCraft 18’. It didn’t come with a tachometer. So I ordered the 79-895283A06 O-8000 analog tach. I just need to know which harness I need to go from the controls to the tach? I know it takes the 5 pin half moon plug at the controls. But finding one that lists my engine is proving fruitless. Am I overthinking it?
 

Dukedog

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purple for power.. blue for light.. black for ground.. gray for tach signal... everything but tha gray can be picked up at any of tha other gauges..
 

Mtcowboyblue

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Oct 15, 2021
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purple for power.. blue for light.. black for ground.. gray for tach signal... everything but tha gray can be picked up at any of tha other gauges..
Thanks for the reply. I have no other gauges. This is a completely bare dash. I will just get plug i think will work and roll with it.
 

Dukedog

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jus for info... plug should have 5 pins.. colors should be:
blk... ground
pur... switched hot
gray.. tach sig.
tan/blue... warning buzzer/beeper
brown/wht... trim gauge

should be a loose tan at tha harness also.. its for a temp "gauge" if your motor has tha sender.....
 

Chris1956

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Mar 25, 2004
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I think you want the harness that goes with the controls. How about harness A-84-86396A4?
 

Mtcowboyblue

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Oct 15, 2021
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jus for info... plug should have 5 pins.. colors should be:
blk... ground
pur... switched hot
gray.. tach sig.
tan/blue... warning buzzer/beeper
brown/wht... trim gauge

should be a loose tan at tha harness also.. its for a temp "gauge" if your motor has tha sender.....
Thanks Dukedog! That is really handy to know for me. Or anyone else thats stumbles across this post.
 

Mtcowboyblue

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Oct 15, 2021
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I think you want the harness that goes with the controls. How about harness A-84-86396A4?
Chris1956, You sir are a gentleman, and a scholar. That’s exactly what I was looking for. I couldn’t find an actual part number that correlated with my engine/control. I already had ordered a harness. But thankfully it matches your part number. So thank you as well!
 

Mtcowboyblue

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Oct 15, 2021
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Well fellas, I finally got the old starcraft out on the water. I am stoked! It was fun, caught a few walleyes and a carp. I did get the aforementioned harness. Pretty sure I hooked it up right. Mercury - Mercruiser 79-895283A06 Gauge-Tach 0-8000
This is the tach that I installed. According to manual, 6100rpms is as fast as I want to spin it. It’s a 2005 115 EXLPT. That sound right to you guys? The tach didn't budge one iota. I have it turned to 6 pole. Any harm in trying other poles? Might have to pull the manual and dive into it again.
 

Chris1956

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Mar 25, 2004
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The tach needs +12VDC, ground and a signal to operate. This power and ground comes from the ign switch. So get out the test light or multimeter and see if she has +12VDC and ground.

As for the tach signal, put a multimeter set to AC on the grey wire on the voltage regulator at the motor, start the motor on the flusher and see if you get some voltage. If so, move the multimeter to the tach signal wire at the tachometer and see if you get the same voltage there.

If you have a 12P setting, you might try that. Mercs usually want 6C or 12P, which ever you have.
 

Mtcowboyblue

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Oct 15, 2021
Messages
6
The tach needs +12VDC, ground and a signal to operate. This power and ground comes from the ign switch. So get out the test light or multimeter and see if she has +12VDC and ground.

As for the tach signal, put a multimeter set to AC on the grey wire on the voltage regulator at the motor, start the motor on the flusher and see if you get some voltage. If so, move the multimeter to the tach signal wire at the tachometer and see if you get the same voltage there.

If you have a 12P setting, you might try that. Mercs usually want 6C or 12P, which ever you have.
Thanks Chris. I can do that.
 
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