New Trim gauge and my 89' 115

Renken1600

Seaman Apprentice
Joined
Feb 10, 2019
Messages
46
Thank you for all your help so far... I am trying to search as much as I can before asking questions.

I recently rewired the boat we acquired and put all new sierra marine gauges. The trim gauge has the purple 12v line coming off of the tachometer.

At the moment, the purple line from my tach is daisy chained to my voltmeter which then daisy chains to my trim gauge. Does the voltmeter interrupt the current needed? Purple wire to 12v, Brown/White to Sender, Black to Ground, Blue to lights... it doesn't seem to work at the moment.

Sierras instructions gives two wiring scenarios for mercury: a wire that piggy backs from ground to sending unit post OR as mentioned above.

If my wiring harness came equipped with the brown/white wire, is it safe to assume I have a trim sending unit on my 1989 Mercury 115 4 cyl? If so... where is it? Can't find part numbers for it which leads me to believe it doesnt have one...

Please help if you can, thanks in advance!
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
The voltmeter does not interrupt any current flow as it is ACROSS the positive and negative lines just like the other gauges. The trim sender, if you have one, is mounted on the engine and may or not be functional. Obviously the gauge will not work if there is no sender or it's not working.
 

Dukedog

Captain
Joined
Oct 6, 2009
Messages
3,463
its on tha port side clamp bracket.. a round sender with two extended "slots" for tha mounting screws.. brown/white wire that should go into tha swivel and come out inside tha cowling.. will plug into tha brown/tan coming out of tha harness..

part number:
8M0098273
 
Last edited:

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,795
Purple or red with purple stripe is 12v power but only when the ignition switch is somewhere besides the OFF position, as compared to solid red wires which are (fused) directly to the battery (+). The daisy chain is just bringing power to all the components needing power (in parallel).

Same with black bringing ground (battery -) to all the components needing the purple wire or just require ground, like the (yellow/black) engine kill, grounded through the ignition switch in the OFF position.
Use specific items, like the (grey) tach signal, and (tan) OT/Low Oil, trim (blue up), (green trim down) are uniquely colored and single terminal connections.

Where there is no terminal, like will happen with my newly installed tach which has 4 pins rather than 4 studs, a wiring crimp barrel is used as the joining mechanism.
 

Renken1600

Seaman Apprentice
Joined
Feb 10, 2019
Messages
46
its on tha port side clamp bracket.. a round sender with two extended "slots" for tha mounting screws.. brown/white wire that should go into tha swivel and come out inside tha cowling.. will plug into tha brown/tan coming out of tha harness..

part number:
8M0098273

Thank you! I will go out and look for this now.

Texasmark, thanks for the wire colours. In an unrelated observation, I have a tan wire that hangs free at the moment. I wasn't sure what it connected to and the diagrams from my manual just ominously says Tan... with an empty bullet connector. If I had an oil temp gauge, is this the sender wire?
 
Top