power trim issues

[myboatisbroke]

OK, i recently installed a power trim unit from a 1992 merc 115 on my 1979 80hp outboard. I bought a brand new 2 wire pump and installed it when I installed the ptt unit. The first issue is, with the wiring exaclty how the wiring diagram says(came pre-assembled) as soon as I hooked it up to 12V, there is a dead short(they had the power hardwired directly to the ground!) I wired it according to a thread I found on here, and I have the same problem. This diagram(http://forums.iboats.com/electrical...-motors/homemade-power-trim-relay-218459.html) shows 87A terminal to be the ground, and the 87 terminal to be 12V+, doesnt make any sense to me, unless I have a dead short in one of the relays now because of the previous issue?

Second issue, how the heck do I prime this thing? I filled it with quicksilver PTT fluid, and the motor spins, but will not raise the motor.

 

[c_douce]

Re: power trim issues

I guess you didn't test it before connecting to your motor? did you buy it from someone? the hydraulics may be shot or could be a relay, if the wires were by-passed, most likely there was an issue. is it making any noise or just not doing anything?

 

[myboatisbroke]

Re: power trim issues

The motor spins, but doesnt raise/lower outboard. and before I put the new pump/motor in, it bench tested fine. I replaced the pump/motor assy. because the bearings in the motor were shot, and the new pump/motor was very inexpensive. My mistake was not bench testing with the new pump/motor. As for the electrical, Im going to get some new relays and going to wire it based off another early 90's boat with the same PTT setup. The electrical stuff doesnt worry me as much as the hydraulic side.

 

[RRitt]

Re: power trim issues

did you mess with the manual release valve? is it closed?

if so, then most likely scenario is that the armature or driveshaft is not properly seated with pump gears. motor spins but gears don't turn. i see people use the wrong driveshaft length all the time when they replace early 1990 motors with newer models.

 

[myboatisbroke]

Re: power trim issues

did you mess with the manual release valve? is it closed?

if so, then most likely scenario is that the armature or driveshaft is not properly seated with pump gears. motor spins but gears don't turn. i see people use the wrong driveshaft length all the time when they replace early 1990 motors with newer models.

I'll check that in the AM, didnt even cross my mind to check that! Hopefully its not the armature issue, the pump and motor came as one unit.

 

[RRitt]

Re: power trim issues

I'll check that in the AM, didnt even cross my mind to check that! Hopefully its not the armature issue, the pump and motor came as one unit.

btw - the circuit diagram you linked will work fine but industry practices usually connect +12v to the switch and ground to the relay coil. then if there is an accidental short it is more likely to blow a fuse and less likely to burn out a relay or motor.

 

[myboatisbroke]

Re: power trim issues

btw - the circuit diagram you linked will work fine but industry practices usually connect +12v to the switch and ground to the relay coil. then if there is an accidental short it is more likely to blow a fuse and less likely to burn out a relay or motor.

Thanks so much for pointing me toward the manual release valve, turns out, it was turned in all the way, but had a bad o-ring. Installed o-ring and worked flawlessly. Put two new relays in, and wired according to that diagram and works exactly like it should! soon as this 2 weeks of downpouring rain stops here, gotta take her out and get some walleyes! Looks pretty slick with the new style power trim, only issue is I had to make two bushings to use the 1979 steering shaft

 

[RRitt]

Re: power trim issues

Thanks so much for pointing me toward the manual release valve, turns out, it was turned in all the way, but had a bad o-ring. Installed o-ring and worked flawlessly. Put two new relays in, and wired according to that diagram and works exactly like it should! soon as this 2 weeks of downpouring rain stops here, gotta take her out and get some walleyes! Looks pretty slick with the new style power trim, only issue is I had to make two bushings to use the 1979 steering shaft

when you get a chance, change your wiring so that the relays have common ground on pin #86 and are controlled by switched +12V on pin #85. It is well worth the 15 minutes of extra time.

You feed the console switch with a 5A fused circuit and control the relays by asserting 12V. It is a much better wiring scheme. The diagram you linked above will be prone to short circuits that will cause trim motor to start spinning during middle of rainy nights in your driveway. By the time you find it, either the battery will be dead or something will be melted.