I have a 90 evinrude 150 and the trim guage works, but only on the top 3/4 of the guage. Meaning when i have it in the full up position the guage is pegged to the top of the range. so i start to lower it through the tilt, when the motor goes down quickly, but the guage does not move. When i get the the slo part, assuming its slow because thats the trim part of the tilt/trim, The guages starts to move. So when it is all the way down the gauge reads 3/4. I was under the assumption it would sweep the entire guage and not just move when its in the trim mode.
I know these are resistance based to get the reading. So is it [possible that the wires are corroding causing high resistance in the system and moving the needle out of the guages range?
does anybody have a diagram for this wiring system?
You could use an ohm meter on the 2 wires to see if the problem is at the sender on the motor.
If the ohm meter reacts the same as the guage then the problem would be at the sender and if the ohm meter shows a consistant increase / decrease they your guage would most likely be faulty.