5.7 mercruiser alarm warning panel wiring

clerihew82

Seaman
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Jul 10, 2007
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57
I have a 1998 mercruiser 5.7 with carb. Last couple of years my alarm has been going off at different times. Sometimes while idling and sometimes when on plane. I want to add some led lights on my dash with each one of the alarm senders so I can see which sender is alarming. Does anybody have an idea how to do this? Do I just come off of the sender wire with a wire and to the led and ground the other side?? I want to do this for the temp sender, outdrive oil sender and oil pressure sender.
 

wrench 3

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Aug 12, 2012
Messages
2,108
Re: 5.7 mercruiser alarm warning panel wiring

You would need to run two more wires from the engine to the instrument panel, install three diodes to stop them from back feeding into each other but still operate the alarm, and run ignition feeds to the LEDs.
If the problem is fairly consistent, why don't you just disconnect the senders one at a time and tape the wire back. When the false alarm quits, that's the culprit.
 

Bondo

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Re: 5.7 mercruiser alarm warning panel wiring

I have a 1998 mercruiser 5.7 with carb. Last couple of years my alarm has been going off at different times. Sometimes while idling and sometimes when on plane. I want to add some led lights on my dash with each one of the alarm senders so I can see which sender is alarming. Does anybody have an idea how to do this? Do I just come off of the sender wire with a wire and to the led and ground the other side?? I want to do this for the temp sender, outdrive oil sender and oil pressure sender.

Nope,... The Senders provide the Ground, ya got it backwards....

Like Wrench says, just Fix the problem, insteada re-engineerin' another nightmare...
 

clerihew82

Seaman
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Messages
57
Re: 5.7 mercruiser alarm warning panel wiring

It is never consistent. I've tried disconnecting senders but it may be every four or five times that I take it out that it will sound. I'm sure it's a wiring issue and checked all connections but can't trace it down.
 

Bondo

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Re: 5.7 mercruiser alarm warning panel wiring

It is never consistent. I've tried disconnecting senders but it may be every four or five times that I take it out that it will sound. I'm sure it's a wiring issue and checked all connections but can't trace it down.

Ayuh,.... Disconnect the sender from the drive oil resv., 'n Run it...

That's the Most likely suspect....
 

Don S

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Re: 5.7 mercruiser alarm warning panel wiring

It is never consistent. I've tried disconnecting senders but it may be every four or five times that I take it out that it will sound. I'm sure it's a wiring issue and checked all connections but can't trace it down.

Did you disconnect senders or the alarm switches. Two different things,
Remove one at a time the temp switch (not gauge sender), oil pressure switch, and low gear lube reservoir sender. One of them is not working properly and going to ground, which causes the alarm to sound.
 

clerihew82

Seaman
Joined
Jul 10, 2007
Messages
57
Re: 5.7 mercruiser alarm warning panel wiring

I disconnected the wire at the senders itself. This was last year so I'm trying to remember the wires
 

Don S

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Messages
62,321
Re: 5.7 mercruiser alarm warning panel wiring

The wire you disconnected better be tan with a blue stripe, or you disconnected the wrong ones.
 
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