Re: OMC Cobra 3.0, tilt / trim gauge available?
You answered your own question. If the sensors are on the outdrive then it is easy enough to add the gauge which is why there is probably no sensor. This was the same delima on my boat, an 1988 as well. If you look at the wiring schematic (assuming you have an owners manual) you should see the wires for the sensor indicated and which color they will be. For a quick indication, look under the dash and see if the wires are present and not terminaled to anything. If they are there it does not mean you have the sensors. Many wire bundles come with all optional wires included in case the optional equipment is included it is cheaper than running more wires. Now then you can use a voltage meter to see if there are signals present. If so you are in luck, now go find a replacement gauge and get busy to mount it. Now you just have to hope the sensors are working properly.
If not then I'd recommend a cheaper option. With the drive all the way down engauge the trim buttom for a few seconds and count it out (one, two, three). Then go look at the drive. Repeat and examine, repeat and examine. You should be able to determine the position of the drive after a few pratice sessions. This of course is while the boat is not underway.
