OK you have 2 extra relays and 4 diodes, need to find them
I'm unable to find the box

swapped out the relays already.

If those were the small square ones, ok
Need a voltmeter and another person. Measure voltage on the end of the diodes that attach to the Blue wires. Measure one at a time, one goes to port and other to starboard. Need to find out if the diode is passing voltage

We did that and no voltage drop.

OK push up and getting 12V on each side of the both diodes

The trim limit will work the same on this system as with separated one. When the up is pressed there should be power on the Blue/Green and Red/Purple (Separated system would be Blue/White and Purple/White shown above).

If power is on one side but not the other then were back to the trim limit on the gimbal ring

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https://cimg7.ibsrv.net/gimg/www.off...cc15edd570.jpg
https://cimg9.ibsrv.net/gimg/www.off...5fe9759fe5.jpg

Add a note: I'm guessing what is going on inside the Mercury box
If a part number could be found or maybe a Merc Super Tech could explain or offer some insight.

I'm assuming that the trim limit is keeping the drive from coming up. The system does not appear to have anything which would measure how high the drive is unless its using the trim gauge wiring, but that wiring is not shown on the drawing.

The box is in the gunnel near the helm seat. You really have to stick your head in there to see it.

https://cimg1.ibsrv.net/gimg/www.off...fc46accfd.jpeg
Here is the black trim limit box. Formula had one left so went ahead and ordered it since the port side started doing the same thing. Hoping it won’t be to hard to install.

Hope it works
Don't know if its worth to reverse engineer, but I would think about maybe remove and replace with old school

After thinking about I have to agree. I’m shipping this thing back on Monday and get pump harness.
Does anyone know the part number for the trim pump harness?