Wiring a 3 wire trim/tilt pump to throttle handle switch

[Captndrydock]

I've recently installed a 1980 Chrysler 115 on my boat from an old junker. My old motor didn't have trim/tilt and this one does. I started to install it the way I took it apart and I'm now wondering if I'm replicating a poor wiring job.

I have 3 wires out of the pump to a connector. Then 8' of wiring harness to the throttle handle. At this point the harness is spliced and steps down to smaller gauge stranded wire. And from there attaches to the switch.

Is this correct? I assumed these older motors didn't use relays, but I haven't been able to find a wiring diagram for a 3 wire pump motor.

Any help is much appreciated!

 

[racerone]

I think some of those used a solenoid for the " trim up " function.

 

[Captndrydock]

I think some of those used a solenoid for the " trim up " function.

Thanks, I'll look into that!

 

[Captndrydock]

I think some of those used a solenoid for the " trim up " function.

My concern was the step down in wiring sizes. Seems like a long run and then to step down. I just found a photo of a new old stock handle and harness and it looks like it has the same kind of wire splice and I assume its stepping down in wire size. It would need to just to fit through the handle. It does work with a thin jumper wire....

 

[dingbat]

My concern was the step down in wiring sizes. Seems like a long run and then to step down. I just found a photo of a new old stock handle and harness and it looks like it has the same kind of wire splice and I assume its stepping down in wire size. It would need to just to fit through the handle. It does work with a thin jumper wire....

Wire size is a function of load over distance. Splicing a smaller diameter wire on to a larger wire equals the sum of the drops of both wire sizes and lengths.

 

[Captndrydock]

After consulting with AI, I've been enlightened about the direct wire setup. Kind of amazing to get this kind of answer from my search browser...

Yes, there is a legacy direct-wire setup for Chrysler/Force 3-wire systems. In this configuration, the high-amperage current for the pump travels directly through a heavy-duty switch in the throttle handle rather than using external solenoids or relays.
This was common on older models (pre-1980s) or systems categorized as "power tilt" rather than "power trim".

Legacy Direct-Wire Diagram
In this specific setup, you only need to manage four primary connections:

• Red Wire (Power): Connects from a 30A fused battery source directly to the center terminal of your throttle switch.
• Blue Wire (Up): Connects from the bottom terminal of the switch to the motor’s "Up" winding.
• Green Wire (Down): Connects from the top terminal of the switch to the motor’s "Down" winding.
• Black Wire (Ground): Connects the pump motor directly to the Battery Negative (-) or engine ground.

Key Identification Features:

• High-Amp Switch: The switch in your throttle handle must be a momentary (ON)-OFF-(ON) type rated for at least 20-30 amps.
• Wire Gauge: The harness wires are typically thick (10 or 12 gauge) to handle the high current without melting.
• Connector: The pump usually has a round or square 3-pin plug that matches the throttle harness.

 

[Scott Danforth]

the switch in the handle is operating the contactors which operate the motor.

no way to run motor wiring thru a switch small enough to make it fit into the binnacle handle

a 20-30 amp switch is going to be fairly hefty

I would use a pair of $2 VF4 relays

 

[Nordin]

As Scott says, you need to operate the T&T with to relays and control them from the switch in the remote control handle.

 

[Chris1956]

My '77 Merc used a solenoid on the up circuit only. The PTT control switch was pretty robust, and the wiring was heavier on the down circuit switch, so no solenoid was necessary.

 

[jerryjerry05]

In the old days: they didn't have a Trim up on the Chryslers/Forces.
The outboards that had T@T usually had a heavy duty switch on the dash and heavy wires from the switch to the pump and battery. Starting around 86 87 they started using relays so they could use the T@T in the shift handle.
If you have any wires that go down in size with a butt connector? that will probably be a HOTTTT spot when activated(don't bury that/them connectors in a loom or harness(fire hazard). To wire a 3 wire motor: simple: Red=battery. Blue(up) Greed (down) Minimum 10/12ga wire and a heavy duty switch.The mounting of the pump completes the ground, make sure it's clean no paint.

Good luck.

 

[Captndrydock]

In the old days: they didn't have a Trim up on the Chryslers/Forces.
The outboards that had T@T usually had a heavy duty switch on the dash and heavy wires from the switch to the pump and battery. Starting around 86 87 they started using relays so they could use the T@T in the shift handle.
If you have any wires that go down in size with a butt connector? that will probably be a HOTTTT spot when activated(don't bury that/them connectors in a loom or harness(fire hazard). To wire a 3 wire motor: simple: Red=battery. Blue(up) Greed (down) Minimum 10/12ga wire and a heavy duty switch.The mounting of the pump completes the ground, make sure it's clean no paint.

Good luck.

Thanks Jerry! Your comments confirm with other info. I should know, I suppose. This is how I removed two of these units from old boats. I was concerned about not having a solenoid or relays. But just not needed with that 10 ga wire as best I understand.

the switch in the handle is operating the contactors which operate the motor.

no way to run motor wiring thru a switch small enough to make it fit into the binnacle handle

a 20-30 amp switch is going to be fairly hefty

I would use a pair of $2 VF4 relays

I removed this set up from another boat. The cable is 10 gauge and drops down to 12 ga at the handle. It did fit the wires and plastic sheathing through the sheathing and wore the insulation off the wires. I may look at widening that hole in the handle so I can run 10 ga all the way to the switch, if possible. Thanks for your comment!
.

 

[Captndrydock]

As Scott says, you need to operate the T&T with to relays and control them from the switch in the remote control handle.

Thanks Nordin! For now, I think I'll just use the 10 ga cable, I see no reason to add relays or solenoid, just to run a smaller wire. Is that the only reason relays are used? I would prefer to modernize the electrical, but for now I'm just going to leave it as originally designed.

 

[Scott Danforth]

The relays are used because of the inrush current of the motor which will take out the switch

 

[Captndrydock]

The relays are used because of the inrush current of the motor which will take out the switch

I see your point, probably best the install relays or solenoid. Although the switch still worked on the old boat I removed it from.

 

[Nordin]

The relays can handle the current that the electric pump motor need to operate.
As I am in Sweden Europe we use square millimeter when we talk about how heavy the wire is.
The pump motor need at least 2,5 square millimeter wire.
It can handle about 15 Ampere DC current constantly but remember the pump motor will draw about 3-4 times that current for a short moment when it starts.
If you use relays the control current which will run through the switch in the handle only will be a couple of hundred milli ampere and the wires only need to be about 0,3-0,5 square millimeter.
And as Scott says the switch has to manage the current too.
That switch in the remote control handle is not heavy enough to manage more than some ampere.

As jerryjerry mention Chrysler used a heavy switch to handle the T&T and they run the pump motor with not using realys and I think your T&T is that typ of stuff.
Using relays is always the best way to go in my opinion even if you have a heavy typ of switch that can handle a lot of current cause it will always be some arcs at the relay when running the T&T and if they fail it is easier to change them than change the switch.

 

[Mc Tool]

Modern 21st century countries use the mm² measurement ...and the metric system . Whenever I see the wire gauge spec I gotta go to the converter app
I an a great fan of fitting relays .....mostly because Im into older stuff and you have to look after switch gear thats nla .
If I had a 50 year old motor that had no relays on the trim pump motor ,even if it was still working fine Id still stick a relay on it ....just me
My Guzzi has been converted to a push button on the handlebar start ,I have a 40a relay off the start button to drive the starter solenoid coz that alone pulls 30a latching current.