'79 mercury 115 trim/tilt wiring issue

jbdmax48

Recruit
Joined
May 12, 2011
Messages
3
hey guy's first post here, been a member a while, doing a lot of reading here, lot's of great info. Working on a '85 cheetah boat that i purchased a few years ago, trying to bring it back to life, the motor is a 115 straight six (mercury), on the tilt i have two wires coming out of the left cylinder, control wires, the jacket on the wires is completely dry rotten, my question is can these wires be replaced by removing the cylinder or are they non replaceable and have to buy a new cylinder? They are bare all the way up to where it goes into the hollow cavity where the cylinder attaches, may be good inside of it but wouldn't think it would be the best location to spice, thanks for any help.
 

Moody Blue

Captain
Joined
May 24, 2004
Messages
3,136
Re: '79 mercury 115 trim/tilt wiring issue

Wire is replaceable. Did that repair on my 71 Merc 800 a few years ago.

Follow the wire down to the cyl. There is a small rect box mouned to the side of the cyl. Two (?) screws hold a cover plate on the box. Inside the box is a micro-switch that the wires connect to. There was also once a small spring in there that has probably long since rotted away, and the switch is most likely seized.

I found a suitable replacement spring, cleaned up the switch (coated in a thick paste of some sort), installed a new wire and hooked everything back up. Works well so far.

Many owners just eliminate the switch completely and connect the two ends of the wire together at the trim pump. Basically you are eliminating the trim limit switch from the circuit.

Here is a wiring diagram to help you understand.

trim wiring.jpg
 
Last edited:

jbdmax48

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Joined
May 12, 2011
Messages
3
Re: '79 mercury 115 trim/tilt wiring issue

Thanks for the info Moody Blue, just the info i needed, trying to put everything back to original, as much as possible. Thanks for the wiring diagram, the pump looks a little rough, maybe do a rebuild on it, the boat restoration forums on here have been a big help, thanks to all you guy's on here for the great info.
 

Moody Blue

Captain
Joined
May 24, 2004
Messages
3,136
Re: '79 mercury 115 trim/tilt wiring issue

Your welcome.

I'm the same way. I hate not having things work the way they are supposed to.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: '79 mercury 115 trim/tilt wiring issue

If you cannot repair or replace the trim limit switch, bypass it with a jumper wire and a couple of bullet connectors.
 
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