Trim up not working but trailer function does

[mhbt]

Hello All, wondering if anyone has any advice on this issue. Reading through the forums, I know this is a common issue on the Mercruiser alpha one's but I am having a bit of difficulty determining what the exact issue might be. So basically, the trailer function moves the out drive up and the trim down function does move the out drive down but the trim up function when you press the switch does not work at all. To troubleshoot, I have pulled the two wires coming from the trim limit switch and used a jump wire (in line test light) to verify if the switch itself is the culprit. When I press the button with the test light jumping between the blue and purple wires, the test light turns on but the out drive does not move at all. From my understanding, this would mean that the switch isn't the culprit since the light activates showing there is power and the switch is operating as intended when pressed; but the motor should be responding as well with it jumped but it isn't. Am I missing something or am I reading the forums wrong and troubleshooting incorrectly? I will take a closer through the manuals and electrical diagrams so I have a better understanding but thought I would ask everyone as well. Thanks in advance!

 

[kulle]

check the ground at the solenoid brackets. sounds like the solenoids are good. i had similar issue and i think it was a llose ground. also pull the limit and sender covers and clean contacts, they can get gummed up.

 

[alldodge]

have pulled the two wires coming from the trim limit switch and used a jump wire (in line test light) to verify if the switch itself is the culprit. When I press the button with the test light jumping between the blue and purple wires, the test light turns on but the out drive does not move at all. From my understanding, this would mean that the switch isn't the culprit since the light activates showing there is power and the switch is operating as intended when pressed;

This only tells me there is 9V+ somewhere, but does not tell me anything. You need a voltmeter and it needs to be read from ground to power lead

You should jump the Purple/White and Blue/White wires going to the trim limit switch.

When UP trim is pressed, 12V should go from the Purple/White to the Blue/White. Check for 12V at the top solenoid on the small Blue/White wire coming from the trim limit switch. If you get power, your switch is OK.

trailer function moves the out drive up and the trim down function does move the out drive down but the trim up function when you press the switch does not work at all.

The trailer function does work for going UP but DOWN does not work.

I'm thinking corrosion or bad ground as kulle mentioned