1995 Mercury 175 Power Trim Relay Switches

[jdevans]

my motor would go down but not up. i inter-changed the two relay switches with each other and the up still didn't work. the down now though trimmed the motor up. what does this mean? which part of the relay switch is bad? the part with the male end or the female end?
thanks,
jeff

 

[jdevans]

Re: 1995 Mercury 175 Power Trim Relay Switches

are there in-line fuses in these relays? could it be a fuse that's blown? where would the fuse be?
thanks again

my motor would go down but not up. i inter-changed the two relay switches with each other and the up still didn't work. the down now though trimmed the motor up. what does this mean? which part of the relay switch is bad? the part with the male end or the female end?
thanks,
jeff

 

[Texasmark]

Re: 1995 Mercury 175 Power Trim Relay Switches

The electric part of your pump consists of 12v supplied via 2 high current switches (mentioned). Being a dc motor, reversing the direction the voltage is applied to the motor reverses the motor. That's what the switches do. The switch is just a switch (on or off; open or closed). If you replaced one with the other it either causes the motor to run the pump or it doesn't. The position the switch is located in (up or down) determines what happens as a result.

Reading in my service manual, there is a thing in the pump called a "shuttle valve". Apparently when you reverse direction via the switches, the shuttle valve is supposed to move from the old position to the new position starting the fluid flow in the new direction.

So I guess if you swapped switches and still have a problem your shuttle valve must not be shuttling to allow a flow reversal.

But there are a couple more valves (or so) in there that react to pressure built up by the moving fluid which could be the problem also. Since there are up and down cavities the fluid has to be directed to the correct one via these valves.

The service manual has a pretty lengthy paragraph describing the operation. Pretty complicated for a simple function........and then there is the pressure relief circuit for when you hit a submerged object to add some more complications.

HTH.

Mark

 

[sleepinin]

Re: 1995 Mercury 175 Power Trim Relay Switches

Jeff,
Is your trim motor "silent" in the direction it's not working or is the trim motor running but just not lifting the engine? If it's silent it may be that your trim relay is bad or a break in the wiring or connector is somewhere in the system. If you put the relays back the way they were then the "likely" bad relay is the down relay which is the one with a Green/white and Green Wires. The one with Lt Blue/White and Blue is the Up Relay. The actual relay part that you need to change is the part attached to the motor plate. Just unplug the wire connector then unbolt the relay from the plate. It's attached with a rubber sloppy connector. I would change both relays, as the other has lived a very similar life and may go out also. They are only about $15 each. If you want to test the Trim motor to be sure it's not motor or pump related you can look at the two relays and locate the green wire on the Down relay and the Blue wire on the Up relay. Unplug these at the bullet connectors(not at the relay) and jump them to power source. Put one on the pos(+) and one on the neg(-). The trim motor should run in some direction. Now reverse the wires by taking the one off pos and putting it on the neg while taking the other off the neg and putting it on the pos. The trim motor should now work in the opposite direction. If this checks out you know your motor and pump are good.

 

[jdevans]

Re: 1995 Mercury 175 Power Trim Relay Switches

Thanks for all of your help. It turned out to be the relay switch. A $15 dollar part, just like you said.
Jeff