Alpha I Trim "Down"

Okay, so I have the outdrive mounted on finally, and now I need to fix the trim wiring. I have a trim wiring diagram for a single-solenoid Merc unit and am positive that 90% of the wiring is correct. However, (3-button trim) when I press the down (IN) button, there is no sound from the pump. When I press up, nothing happens, however when I hit the "up" and "up/out" buttons I hear the pump click like it would if it was at a trim limit.

Possible issues: this unit has the separate trim limit switch and the trim position sender is mounted on the transom plate, and wiring issues that would activate the trim limit switch? Trim guage does show unit all the way up when it was up in the trailer position (put there manually).

The hydraulic hoses coming from the trim rams through the transom could be switched. Both of my hydraulic lines are the same size and shape, so I didn't know which is the high-pressure "up" line, and the low-pressure "down" side. Could crossing these cause the pump not to activate?

Finally, the entire system was pretty much evacuated of oil. I did fill the resevior back up with about 2/3 of SAE30 oil as specified on the pump base. I have no doubt the lines need to be bled, but it's difficult to bleed the system when the pump doesn't operate.

Any help would be appreciated as we will attempt to fire the engine up next weekend and a working trim pump would be desirable.

Re: Alpha I Trim "Down"

newbie here, so bear with me.
1) are the batteries fully charged?
2) did you check the fuses for the trim pump?
3) did you check the connections at the pump itself?
4) did you state that you repaced the trim limit andsignal switches on the outdrive of the boat? it's possible that you crimped a wire while replacing the bellows .
as far as 90% sure, they aren't overly involved. double check your connections to the instructions. If you get this , and need a brush up on the directions, I have them

Re: Alpha I Trim "Down"

From what i remember the solenoid controls the "UP" the down motor lead is wired to the "IN" button .
remove the connector plug at the pump unit,
jumpering 2 of the connections make the pump work .use a test light to determine the 12V one and then jump from there to the other lugs.
Make sure the pos and neg power cables are clean and connected tight.