Powertrim relay melting / Welding with a powertrim relay

Hello,115 mercury from 1993 is having a problem with its powertrim.

So now and then the relays keep sticking, so the engine keeps going up/or down after letting the trimbutton go. Not always, but especially when it draws high current (like when i trim up, when i am going with a bit of speed).

I understand that the current is to high, and that that is the reason that the contacts in the relay melts, and keeps sticking. But why is the current to high? What can be damaged that is making the current so high?

By the way, i am not talking about the solenoids. Those seem fine.
The relays are:
My 115 HP mer

If the brushes are worn in trim motor amp draw will be high....

If thats the case, that sucks. Cause it seems the brushess are no longer available at Mercury.

So do we have any solutions? Heavier relays perhaps? Or flyback diodes across the coil of the relais?

Heavier relays will cause wire and insulation damage, just use amazon to find replacement motor. DB electric has good stuff...

faztbullet said:

Heavier relays will cause wire and insulation damage, just use amazon to find replacement motor. DB electric has good stuff...

Click to expand...

You are right. Thank you.

By the way, why does my Merc have 2 sets of powertrim relays?

The 2 red circles are two trim solenoids. But in the yellow circle there are 2 normal SPDT relays. The two solenoids are original because they are fitted onto the motor. However the switching side of the solenoids are going to the SPDT switches (controlling the SPDT relays).

Are the two smaller (SPDT) relays installed later? (not original)? Because i cant find them in the parts list of this engine.

The Blue and green wire from the control on the throttle go to the solenoids. NOT the SPDT relays

By the way, the motor on the trim is a 2 wire motor. Not a 3 wire. I have the feeling that 3 wire is original and that those relays are installed together with a 2 wire trimmotor.

Its been coverted to a 2 wire motor. The square relay flip/flop output and ground as for up blue is pos and grn is neg and vise verca for down . The round solenoid cannot do this with a 2 wire motor.

Thank you.
You are right.

But i did some thinking. The fact that the relays are frying together is not because of the continious current that runs when the engine is beeing trimmed up or down. A DC motor is a inductive load, which means it stores a electromagnetic field within itself when a current is passing trough it. This EMfield collapses when the engine stops trimming (ie when button is let go). This gives a massive voltage spike, which creates an arc on the contacts of the relay. I dont think its the brushes that create this problem.. I did order some new relays that are rated for 70A. (resistive load). We will see how the handel the inductive load.

Need to remove the round solenoids as may be feeding back a pos to a neg when activating and welding contacts. There is something wrong with wiring or motor as they(OMC & Merc) have been using these 30 amp relays for years with no kickback

Are the relays of the original trim system only 30 amps? The contacts seem much much heavier than that (internaly)

Different trim motor as original was a field and frame style an draws more amps...magnet style not as much draw.