Trim Relays keep blowing

[shane3971]

I have a 1986 Mercury Black Max XR2 with trim problems. I have changed the 4 post relays TWICE and they keep going out after 3 or 4 trips. Both aren't going out, it's either the up relay or the down relay. Any ideas why this keeps happening??? Few day left before daylight savings time and wanna get some fishing done after work....

 

[alldodge]

What size fuse is in on the trim pump?
Are you using Mercury relays? If not what kind and part number are you using?

 

[shane3971]

I will say they are NOT Mercury replacements....no mercury dealers within 30 miles of me. Its an auto parts store replacement. Not sure what size fuse is on the trim pump. I have an inline glass fuse but it's not blowing. The up relay just quit on me. The down is working fine and when I jumped it the motor went up no problem...

 

[alldodge]

If the fuse was higher then 20 amp, then it was replaced
If fuse was a higher amperage then the motor could be drawing more current

So everything is as it should be but your blowing relays. This tells me that the relays your buying can not handle a solid 20 amp load and the contacts are giving out. Most Auto relays can not handle the surge current the motor needs to start. I would suggest getting any of the outboard motor relays Merc, Johnson, etc they can handle more load. As an example, here is a Johnson and it shows 30 amp contacts

http://www.ebay.com/itm/Johnson-Evi...ilt-Relay-584416-586224-18-5705-/182290322385

Either that or see if you can find at least a 30 amp relay at the auto store

 

[shane3971]

I appreciate the replies. I'm definitely gonna get the correct Mercury relays and see if that fixes it. Thanks again

 

[gm280]

Which part of the relays are going out? Can you hear a clicking noise when you move the trim switch either up or down from the relays?. It would be great to know if the coil is burning out or the contacts are burnt out. Different reasons for those two issues. JMHO

 

[shane3971]

Well I'm probably calling the "relay" by the wrong name. Its actually called a solenoid by what I'm reading. 89-96158T is the part number. I had the down solenoid go out about a month after I bought the boat and have since changed the up AND down again since then. NOW the up solenoid went out on me last Saturday. I was using an auto parts store replacement that I'm assuming wasn't the right amperage. I have changed ALL the wires and connectors too so I know the wiring is good. Like I said earlier I have ordered the EXACT replacement needed. Sorry for the confusion and thanks again for the help. Hopefully this fixes the problem. Little frustrating when you are up river 7 miles from the launch and trim goes out.

 

[gm280]

shane3971, you didn't answer whether you could still hear a clicking noise when you try to trim. If you can then the contacts in those replacement relays are your problem. But it you can't hear any clicking sound when trying to trim, you have coils burning open. Those two things are caused by different issues. JMHO

 

[Grandad]

Welcome to iBoats Shane. Did the original relays perhaps have a "flyback" circuit? Often diodes are placed in parallel with coils (reverse biased/polarized) such as exist in the winding of your trim motor. When the relay opens, the strong magnetic field in the winding collapses. This collapse of the lines of force induces a current flow opposite in polarity to the normal operating DC circuit. As the control circuit is opening, this newly generated circuit produces an equal and opposite current flow that can burn the relay contacts. A flyback diode placed in reverse polarity across the coil/winding will oppose current flow when the coil is energized, but instantly allows reverse current flow generated by the collapse of the coil's magnetic field to be shorted harmlessly, prolonging the life of the relay and/or switch contacts. You could easily add diodes. I'm not familiar with your circuit, but a correctly placed diode could help. You can't use a diode if the circuit requires polarity on the coil to reverse, in which case, I'd try a suitable resistor in parallel, rather than a diode. Here's an explanation with illustrations that might help. - Grandad
http://www.douglaskrantz.com/ElecFlybackDiode.html

 

[shane3971]

These are the solenoids I have. One for up and one for down.

 

[shane3971]

Gm280...I don't hear clicking when I trim up. There is no noise at all when I try and trim up

 

[Silvertip]

If you had been buying a generic solenoid, are you certain you are buying 12 volt units and not 6 volt units. They look the same but the 6 volt units will not tolerate 12 volts.

 

[gm280]

shane3971, I realize they are usually called solenoids, but in reality they are just larger relays. You are controlling them via a small switch to pass a large current to the trim motor. If you are not hearing them click when you try to trim, then you are burning up the coils inside. That isn't the problem of the contacts not being able to handle the current, that is the switch circuit carrying too much current to the coils. If you are not buying the wrong voltage types, then you have something else causing that problem. JMHO

 

[bruceb58]

If they are truly 12V coils, apply 12v manually to the coil to see if they click and operate. Could be the only problem is your trim switch and/or the wire that feeds it has a resistive connection.

 

[alldodge]

Gm280...I don't hear clicking when I trim up. There is no noise at all when I try and trim up

With these being your relay's then your not blowing them as Bruce mentioned

I should have dug in further but your saying there blowing them, they probably are not. You probably have a problem in the wiring or the trim switch it self. One of the small terminals is hot and the other is ground. When one won't move anymore, connect 12V to the switch side of the small terminal, it should work. If it does start with the trim switch and wiring