?84 75hp Johnson ? intermittent trim tab

Rockchalk

Petty Officer 3rd Class
Joined
Jan 10, 2005
Messages
82
My trim tab on the ole motor is acting up. It will trim up but not down. It does this every once in a while (in the middle of a fishing trip) then will mysteriously start operating fine again days later. I pulled the control handle apart last night and checked the switch by touching a short wire to the center post and then each side? got action going up but not down so I think the switch is ok??? I also pulled apart the little wire connection terminal (pardon my lack of proper name? I?m not a mechanic) mid boat to see if it was the cause (I had here it can cause T/T issues) I cleaned and think I have a good connection. So the question is what remains. Electrical??? Hydraulics???

I opened the fuse box and took a look at the Bosh relays (are they relays?). One clicks when I hit UP and trim raises? the other does nothing when I hit DN. Is there a simple test to see if it is the DN relay??? How hard are these to change out???

Can something physical in the T/T cause this failure??? Fluid level??? Sorry so long winded? have a trip planned and I am trying to avoid another ride to the mechanic. Thanks in advance for ANY help!!!
 

Gary H NC

Fleet Admiral
Joined
Dec 1, 2005
Messages
8,972
Re: ?84 75hp Johnson ? intermittent trim tab

Most likely its a bad connection. Clean all the contacts at the relays,just don't look at them take them off and clean them up. The relay may be bad but you need to rule out connections first.
 

Rockchalk

Petty Officer 3rd Class
Joined
Jan 10, 2005
Messages
82
Re: ?84 75hp Johnson ? intermittent trim tab

Thanks Gary? didn?t think of that. I?ll give it a try tonight. I assume you mean clean the few wire terminals exiting the relay and connecting to the fuse box... the wiring into the relay appears to be wired direct. How hard is it to swap out relays?
 
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