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ContinuousWave: Small Boat Electrical
Replacing Voltmeter with Tilt Gauge
|Author||Topic: Replacing Voltmeter with Tilt Gauge|
posted 05-03-2008 05:58 PM ET (US)
Hi. I have an 2007 160 [unrecognized acronym] with standard gauges: tachometer, voltmeter, fuel, and water pressure. I would like to replace the voltmeter with the same size tilt indicator gauge. I have a voltmeter on my chartplotter. Can I just disconnect the wires to the voltmeter, tape them off so they don't short with anything, and replace [the voltmeter] with a tilt gauge? My concern is whether the voltmeter needs to be connected to complete any circuits or other functions.
posted 05-03-2008 10:40 PM ET (US)
The voltmeter doesn't complete any circuits. There will
probably be three wires on it: the voltage being measured,
ground, and maybe power to the light in the gauge (usually
this is wired to the running lights, sometimes to a wire that
gets hot when the ignition is on (bad idea, IMHO)).
If you have three wires on the voltmeter, then you need to
And I wouldn't tape it off. I'd wrap heatshrink around it.
posted 05-04-2008 10:54 AM ET (US)
Excellent. Thanks very much for the help. Sometimes something that seems so simple and obvious can cause many unexpected problems when everything is somehow linked together. Again, thanks.
posted 05-07-2008 09:21 PM ET (US)
You don't need to tape anything off. The "voltage being measured" is usually the purple ignition hot wire. You also need that to supply +12 to the trim gauge. The trim gauge also has ground (black) and lights (blue) which are the same on the voltmeter. Just move them over. You will be adding one new wire, which is the trim sender feed (brown-white in most wiring bundles, at least for Merc). The other three are the same on both gauges.***
***Unless you have a voltmeter that works all the time, not just when the ignition is on, then it's slightly different.
posted 05-11-2008 01:16 PM ET (US)
Thanks for the additional information. I just rec'd a new Trim Gauge without connection instructions, and would appreciate help on wire hookup. The gauge has the following wiring notations: "S", "I", "G" and a blade connection with "L".
posted 05-11-2008 01:25 PM ET (US)
The legends on the gauge are interpreted as follows:
I = IGNITION, a source of +12 volts which is wired from the ignition switch and hot in the RUN position; usually carried on a conductor with VIOLET insulation (that's PURPLE if you are a fisherman);
G = GROUND, the battery negative terminal or bus; usually BLACK or YELLOW insulated conductor. In OMC installations an isolated ground conductor is used which carries to the engine and connects to a ground common point associated with the trim sensor; this conductor has BLACK with TAN stripe insulation.
L = LAMP or ILLUMINATION, the gauge illumination circuit, usually carried from a switch that controls gauge lighting and carried on a conductor with BLUE or LT BLUE insulation; often run via a jumper from an adjacent gauge.
S= SENSOR, a lead to the trim sensor on the engine; usually carried on a conductor with WHITE with TAN insulation.
posted 05-11-2008 01:31 PM ET (US)
Exactly what I needed. Thanks very much.
posted 05-11-2008 02:31 PM ET (US)
You didn't say what brand of motor you're working with. If it's a Mercury the color code is slightly varied. See the REFERENCE article on wiring color codes for some clarification:
posted 05-11-2008 02:58 PM ET (US)
Jim--The motor is a Mercury 115-HP Four Stroke circa 2007. I am hoping I can find a trim gauge wire at both ends not connected to anything in the wiring harness. Mike
posted 05-14-2008 10:04 AM ET (US)
In my Mercury motor wiring harness bundle the TAN insulation looks more like BROWN, but it's the same thing.
There is no return wire, one side of the sensor pot is grounded to the engine frame right under one of the mounting screws. And hence the ground terminal on the gauge goes to general console ground (black).
The wire you need should be in the bundle. The aft end is taped or tie-wrapped to the rest of the wiring just inside the engine cowling where the rigging hose enters. The console end might be harder to find depending on how much they taped or tie-wrapped loose wires inside the console. I may have also had to remove the battery to see what was going on. In a Montauk 170 the batery blocks the first foot or so of the wiring bundle as it enters the console.
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