trim and tilt relays overheating

[matty marine]

I have a 1979 150hp Johnson and the up relay overheats and melts. all the connections are solid and it still burns up. What am i doing wrong?

 

[emdsapmgr]

The 79 system uses a 3-wire trim motor and a remote-mounted special relay box. The relay box is connected direct to the battery for it's own power source. It's usually mounted inside the boat. Does your system utilize that special box? That box comes from the factory with a wiring diagram, glued to the inside cover. Is it wired to that printed configuration? Is there a small 20 amp fuse as part of that circuit-it should blow first.

 

[matty marine]

The box is there but they installed it on the powerhead and the cover is gone. If i switch the wires on the relays from the tilt motor it goes up and the down relay sticks and i have to un plug it

 

[matty marine]

is the whole box supposed to have power? And olny the trim motor is grounded out. there is a ground wire coming fromthe control box harness to the box and screws in the plastic is that supposed to have a secondary ground wire coming out to the common ground?

 

[emdsapmgr]

Something does not sound right here. Your 1979 engine's trim box came from the factory with a single solenoid. The motor was s a 3-wire motor. Later years (after around 1981 or so) the motors changed to 2- wire motors and the control box was mounted under the cowling. The single solenoid was replaced with two trim relays. You say you have a 79 system, but are talking about trim relays. Sounds like someone has merged parts from two different systems. Unless it was converted to a 2-wire motor. Parts for both systems are not compatible. That could be the problem.

 

[boobie]

How many wires go to your tilt/trim motor ??

 

[matty marine]

3, green blue and black. And i think emdsapmgr was right some one scabbed togather two systems and i got their nightmare

 

[emdsapmgr]

So, you've got a stock 3-wire trim motor with a later model 2-wire trim box. Need to look around for a used trim box for your 1979 year. You can check out the specific 1979 parts needed from the factory parts diagram website: epc.brp.com These trim systems were used by the thousands back in the day. Marine salvage yards likely would have an inexpensive salvable used box.

 

[gm280]

A relay used in a trim motor setup is synonymous to a starter relay/solenoid setup. The trim motor uses more current then a simple switch can handle and therefore you need to use a relay to handle the current. So if you understand that current concept, you can see how such relays are wired. If a relay is getting hot, especially hot enough to melt, something is not wired correctly or your trim motor has some issues as well. The contacts of the relay should be the only part of the replay that carries lots of current, never the relay coil itself... So research how it should be wired and follow that schematic diagram... JMHO!

 

[matty marine]

So i found the correct single solenoid box followed the instructions on the inside to the wire map and presto! It all works right. This was truly a learning experience. Thanks guys for knolage. I've been a boat mechanic for 14 yrs now and i was so focused on why the relays wernt working i never noticed the system didnt belong. Im glad this site was put togather and i hope i can pay some knolage forward in the future.