Trim/Tilt gauge operation

[j1zajac]

I have a '90 Thompson with 5.7L i/o Mercruiser unit. About two months ago I replaced the trim switches and at the time the dash gauge and unit operated fine and to spec. Now the trim/tilt gauge doesn't fully sweep upward when the i/o unit is tilted to the full up position. The i/o operates fine and the trim switches on the i/o are tight and secure. The gauge only sweeps from the full bottom position to about 3/4 of the way up with the i/o fully extended upwards. Is there a way to check the function of the gauge to determine whether it's defective instead of just buying a new gauge and finding out it was good,thnaks.

 

[SingleShot]

Re: Trim/Tilt gauge operation

I would check the sending unit first. On the outboard versions the sending unit is just a reostat or variable resistor. The guage is just a current meter. As the motor swings up/down the resistance changes as will the current. Your guage reads/measures this. You could unhook the wire from the sending unit (brown w/white) typicaly. On merc outboards this is usualy a brown w/white tracer. If you have access to an Ohm meter just measure the resistance from that Brown/wht wire to ground on the boat. You should see the resistance swing up and down as you trim the motor. On my 125 outboard the resistance is about 30ohm lowered to about 150 ohms raised. The resistance will not be centered as you motor trims up higher than lowered. What you want to look for is the resistance to not stop at one point but to constantly increase or decrease as long as the motor is trimming up/down. If the resistance measured stops while moveing the motor up/down you may have a bad spot in the sending unit. Your guage should be ok.<br /><br />SingleShot

 

[j1zajac]

Re: Trim/Tilt gauge operation

Thanks......