Drive trim acting odd

Stodge

I've noticed that the switch on the throttle for drive trim is moving 1 drive up but both drives down.  The individual switches on the shifter housing work correctly.  Does anybody have the wiring diagram for the trim switches to help me track this gremlin down?

Handymans342

It may be the trim pump solenoids. 

jhofmann

If the trim works correctly using the switch on the shifter housing, I think the pump solenoids are working correctly. 

Stodge

The individual switches work, it's just the switch that does both drives at the same time.  If the solenoid was bad I'd expect the individual switches to not work.

Handymans342

Must be the switch then

Stodge

Well I'd think that too, but it's a single pole switch.  Only 3 wires come off of it.  So it "should" do both or nothing.  That's why I'm curious how it's connected.  I want to see how a single pole switch can make both drives go up or down while the individual trim switches still work.  I can't see where the wires connect.

mvn

The only way that I can think of is a system that uses isolation diodes in the circuit.  Do you have a model number of your controls?  I may have a manual.

Mark

mvn

Hmmm....have a look here.  There is reference to a diode pack which makes sense.

Mark

Stodge

Not 100% but it looks a lot like images of the 883711a03

mvn

Looking at an online parts breakdown, I don't see a separate diode pack in a 4500 Gen II control.  Without having any knowledge of the wiring of one, I would closely look at the single trim switch harness (specifically the connector where it plugs into the main harness.  Look for anything odd.  The diodes may be buried in the single trim switch harness and may not be a discrete device.

Just guessing here........

Mark

Stodge

I will have to do some digging to find where the switch plugs into the harness.  It's not in a spot easy to see.  

Thanks for the info.

jimzimm

Check the up solenoid on the trim pump, should be able to jumper between power and green/blue wire to run pump. Probably the up solenoid and/or the trim position sender is bad or out of adjustment. I assume you have a Bravo 3. New complete pump with SS bracket is $400 from SEI in Florida.

georgec14

alswagg is 100% right.the switches override  the limit sender.

Handymans342

Al is always right

Stodge

Any way to by-pass the sender to test?

mvn

Not sure where the trim limit switch connector is but you could just jumper it for testing.   Make sure it's the limit switch and not the position sending unit. 

Mark 

vyborny1

 I had the same problem that when I hit the button on the port throttle, only the port drive would move. I would have to use the individual buttons. Well, this spring, I went to push the button & it completely fell apart. I could not trim my starboard up or down. I jumped it & was able to move it that way. 
I went on line & was able to find a page that sold all of the parts ( www.marineengine.com). I was able to find new piece, so a week later & $130 here it is.   So, I had to take apart the whole throttle, had to take out the ice maker & squeeze my way down the side of the bench seat. Luck, everything is plug & play. 
If you see the 2 buttons & the connector, that plugs into 1 coming from the port throttle, then goes down to its own connector. I think this what controls both drives. 
I now can control both drives with the 1 button
I hope this helps someone in the future.    

zaverin1

Sender wires go
via the transom assembly into the boat