I recently noticed two frayed wires inside of my boat. The trim gauge has not worked in awhile, so I thought maybe these two wires are for the trim unit (one on each side of the lower unit). In tracing the wires, I noticed that they go from the trim unit in the boat to through the transom. They have bullet ends (in the boat) that connect to a harness, and one of the ends is green, and the other is purple. Trim works fine, but gauge doesn't read...is this why? Also, I assume it's ok to use the boat without these units be operational, right? If so, how low can the motor go while motoring, and will it automatically stop in the highest position before it does any harm?
Im guessing this is a Mercrusier. Anyway the port side of the drive (under the plastic cover, at the gimble pivot point) is the "trim limit" Trim limit is the switch that stops the drive from going to high when trimming up. The switch on the starboard side is the "trim sender". The trim sender is for your gage. If the trim sender's wires are frayed they will stop the gage from working. If the wires are frayed on the trim limit it will blow a fuse at the trim motor and the drive will not go up or down. Its a real pain to replace these wires. They can be bypassed inside the boat by hooking the bullet connectors to themselves. It you ever bypass the trim limit dont raise the drive while underway to far (let say about 30-35 degrees) This will put stress on the u-joints. Bypassing the trim sender will get you no where. Dont worry about the gage. Years ago we never had gages and people used their boats just fine. hope this helped some.