Wiring a 1984 150 Merc V-6 Temp Gauge

JimDD

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Jul 28, 2009
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16
In the past 3 years, I disabled my oil injection for this motor due to recurring nuisance alarms, and began mixing my own oil in the gas tank. I installed a water pressure gauge and it is working fine as far as alerting me to water pressure problems. Problem is that when I demoed the oil injection electronics, I also removed my temperature alarm functionality.

I believe to fix this back to functionality, my thinking is that I would need to rewire a conventional circuit using the temperature sensor I have to the alarm horn under my console. This model motor did not have the alarm in the throttle control box as some have.

My problem in looking at an original factory service manual, it is not real clear on how to wire this situation up. Does anyone maybe have a solution or reference for me?

Thanks for the help.
 

Laddies

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Sep 10, 2004
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Re: Wiring a 1984 150 Merc V-6 Temp Gauge

You have 2 wires from the sender one goes to ground the other to a junction block, there should be a tan/blue wire from the horn that you disconnected, hook the sender wire at the block to the tan /blue from the horn and it will work to test turn the key to the on position and short the wire at the block to ground and the horn should blow.
 

woodchuck

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Jun 1, 2007
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Re: Wiring a 1984 150 Merc V-6 Temp Gauge

JimDD did you check to see if your alarm works?
 

JimDD

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Jul 28, 2009
Messages
16
Re: Wiring a 1984 150 Merc V-6 Temp Gauge

You have 2 wires from the sender one goes to ground the other to a junction block, there should be a tan/blue wire from the horn that you disconnected, hook the sender wire at the block to the tan /blue from the horn and it will work to test turn the key to the on position and short the wire at the block to ground and the horn should blow.

Laddie,
Actually, my overheat sensor has only the one wire (tan and blue stripe). With the one wire, the original overheat function detection was provided when the sensor detected high temperature, closed and completed the circuit making the console horn alarm blow. The part I lost when I demoed the OI was the overheat sensor circuitry power. The OI module had power from one of the switchboxes. What I need is to have a safe way (without the oil injection module) to power the overheat detection circuit when the key is on.
:)
Thanks.

JimDD
 

JimDD

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Jul 28, 2009
Messages
16
Re: Wiring a 1984 150 Merc V-6 Temp Gauge

JimDD did you check to see if your alarm works?

Woodchuck,
Yes I did by putting a 12V source to the thing and it still blows a shrill high pitched sound. Good advice though.

Thanks.
 

j_martin

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Sep 22, 2006
Messages
7,474
Re: Wiring a 1984 150 Merc V-6 Temp Gauge

Laddie,
Actually, my overheat sensor has only the one wire (tan and blue stripe). With the one wire, the original overheat function detection was provided when the sensor detected high temperature, closed and completed the circuit making the console horn alarm blow. The part I lost when I demoed the OI was the overheat sensor circuitry power. The OI module had power from one of the switchboxes. What I need is to have a safe way (without the oil injection module) to power the overheat detection circuit when the key is on.
:)
Thanks.

JimDD

1 amp fuse from the purple key on wire under the dash to the sonalert should do it.

Shouldn't sound unless it's actually hot. no power on beeps.

hope it helps
John
 
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