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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3854
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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My power trim pump does not activate to move the out drive

Customer Question

My power trim pump does not activate to move the out drive up but works moving it down. I disassembled the unit this last winter and suspect I might have missed a cable. I connected the blue and white cable from the pump to the positive 12V and the pump worked fine. The trailer position button moves the drive up. Is the limiter the problem? How do I approach this problem? It is a Mercruiser system for a Bravo 3 drive.
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.
Hello, my name is***** will assist you. Where does that red wire in the pic belong?
Customer: replied 1 year ago.
The small red wire connects between the main + in and the back side of the solenoid through a fuse. I cannot see exactly where it connects without disassembling
Expert:  Charles replied 1 year ago.
Ok, so it is hooked up then. Do you have more than one trim switch on your boat?
Customer: replied 1 year ago.
No. Only one.
Expert:  Charles replied 1 year ago.
Ok, you will need a helper and a phillips screwdriver to test out the limit switch. Do you have both?
Customer: replied 1 year ago.
Yes
Expert:  Charles replied 1 year ago.
Ok, on the side of the drive is two senders, one for the trim gauge and the other for trim limit. Locate the trim limit sender and loosen it. Have the helper in the boat, hold the trim switch up while you loosen and rotate the limit switch. See if the unit will begin to trim at all.
Customer: replied 1 year ago.
Ok. But first, I just replaced the transom and have not connected any wires between the transom senders and the power trim assembly. Is this correct or should I have connected the limiter?
Customer: replied 1 year ago.
By the way, the new transom is smart craft enabled in case that affects this wiring
Expert:  Charles replied 1 year ago.
You will need them connected before it will work as it should. Or we can accurately troubleshoot the system.
Customer: replied 1 year ago.
Ok. Where can I locate these wires? And where should they be connected to?
Customer: replied 1 year ago.
I can see a red, white and blue cable with a smart craft connection. I am presuming this is for the gauge or is that also the limiter? I cannot see other wires
Customer: replied 1 year ago.
Did some homework on my end and it turns out that the smartcraft enabled transoms only had a single sensor with the mentioned three wires. It plugs nicely into a slot on the engine although I am not confident it is the right one. It made no change after connecting however. I am not understanding how the transom limiter can speak with the pump assembly though
Expert:  Charles replied 1 year ago.
It functions through the switch in the control handle. Do you have a multimeter to tet the wiring behind the control handle?
Customer: replied 1 year ago.
Yes. I can do that. But my handle is from -98 and thus not SC enabled. I don't see how the handle communicates with the engine. Does a SC transom require any special handle? Was communication previously made with wires directly between the handle and the transom limit sender?
Expert:  Charles replied 1 year ago.
What year is the engine?
Expert:  Charles replied 1 year ago.
Do you have the serial number from the transom assembly?
Customer: replied 1 year ago.
It is a 383 Stroker from 2015. The transom is a smartcraft bravo from 2015 as well. These were not replaced simultaneously and the power trim worked fine with the old transom.
Expert:  Charles replied 1 year ago.
Do you have the transom assembly serial number?
Customer: replied 1 year ago.
It is 2A480267
Expert:  Charles replied 1 year ago.
Thanks, ***** ***** have a meter to test the circuits under the helm?
Customer: replied 1 year ago.
Yep
Expert:  Charles replied 1 year ago.
Locate the trim harness coming from the control handle. Test between the blue and the red wires for voltage while a helper presses the and holds the up switch. See if you can get power between the two wires. Use the black wire from a gauge for the ground for the meter.
Customer: replied 1 year ago.
Would I connect the plus side of the multimeter to the red cable and the minus to ground and subsequently the same with the blue? I don't know what exactly you mean by voltage between the two cables with a third ground
Expert:  Charles replied 1 year ago.
Yes. that is correct. Somehow in my writing, my resistance test and the voltage test came out at once. Between the red for the trim and the black on the gauge, there should be 12V. Then when holding the switch up, you should get 12V on the blue.
Customer: replied 1 year ago.
I am getting a constant 12V on the red but nothing on the blue when holding the switch up
Expert:  Charles replied 1 year ago.
does the trailer switch still work after hooking up the sender?
Customer: replied 1 year ago.
Yes, it does.
Customer: replied 1 year ago.
There is no reading on the gauge
Customer: replied 1 year ago.
Can you explain where exactly to connect the transom SC plug to rule that potential error out? I currently have it connected to a socket right by what looks like a distributor cap on the top of the engine
Expert:  Charles replied 1 year ago.
That is the correct plug.What you have is a failed trim up switch and it needs to be replced.
Customer: replied 1 year ago.
This is a brand new transom assembly. Are you sure that is a likely problem? Any other things we can do to diagnose?
Expert:  Charles replied 1 year ago.
Th switch in the control handle. Not on the transom.Is there a plug in with the red/blue/and green wires in it near the control handle?
Customer: replied 1 year ago.
Would not the gauge work if it was only the switch that was defect?
Customer: replied 1 year ago.
Yes. There is a white plug with the individual cables connected to it
Expert:  Charles replied 1 year ago.
Alright, unplug that connector, take a piece of scrap wire and strip each end. Touch between the red and the blue wires. Does the trim pump activate?
Customer: replied 1 year ago.
No. No activation.
Expert:  Charles replied 1 year ago.
Did you do that on the handle side of the plug or the harness side?
Customer: replied 1 year ago.
Harness side. Was that correct?
Expert:  Charles replied 1 year ago.
Yes it was.Inspect the wiring from the helm to the pump. Something may have became unplugged, and that is not allowing the switch to work. You can also do a resistance test on the handle trim switch. Test between the red and the blue, using resistance, with that plugin disconnected. Have your helper move the trim switch from off to the up position and see if it will make a connection.
Customer: replied 1 year ago.
Am I more specifically tracing the red and blue cables from harness to the pump?
Expert:  Charles replied 1 year ago.
If you tested the trim switch and it is good. You are looking for something to be wrong from the helm to the engine, to the trim unit, on the wiring for the trim.
Customer: replied 1 year ago.
FYI - working on this. Will revert soon.
Expert:  Charles replied 1 year ago.
No worries. There are no time limits here.

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