Bennett ATP Install C-28 - Power Source Needed

M

Miacuelli

Member
Joined
Sep 21, 2025
Messages
8
Fluid Motion Model
C-28
Vessel Name
Freja
I am in the process of installing the Bennett ATP and I am having a hard time figuring out how to get power to it, specifically:

The factory setup has the trim tabs powered off the house battery system

For the ATP install I need:

  • Ignition on power (So that the helm control is not on all the time with corresponding LEDs)
  • Engine ON/OFF signal to automatically raise the trim tabs when the engine is turned off

Based on my research so far all I have come across is a reference to an additional wiring harness/relay that can be added to the engine, but the details are sparse.

Any help / insight would be appreciated !
 
I am assuming that you have a C28 inboard Volvo D4. If so here is information. I installed an exhaust and water flow alarm in my C26. I needed this alarm activated when the start switch and EVC panel was powered. I purchased a Volvo Data link cable and plugged it into the Data link terminal block (Located at the helm follow wire harness from EVC to find it) There are several wires coming out of the harness. Using a VOA meter set at DC turn the start switch on to find which wires have 12V power and ground when the switch is activated. I used the 12V+ and ground wires from the harness to power the alarm system. When the Fob is used to turn the start switch on. I wired the Data Link cable B+ and B- to a relay. Then supplied the relay with a power supply to power the alarm system. I would do the same for the application you are using the ign switch power for. Relay closes with 12V, opens when 12V removed.
 
BB marine said:
I am assuming that you have a C28 inboard Volvo D4. If so here is information. I installed an exhaust and water flow alarm in my C26. I needed this alarm activated when the start switch and EVC panel was powered. I purchased a Volvo Data link cable and plugged it into the Data link terminal block (Located at the helm follow wire harness from EVC to find it) There are several wires coming out of the harness. Using a VOA meter set at DC turn the start switch on to find which wires have 12V power and ground when the switch is activated. I used the 12V+ and ground wires from the harness to power the alarm system. When the Fob is used to turn the start switch on. I wired the Data Link cable B+ and B- to a relay. Then supplied the relay with a power supply to power the alarm system. I would do the same for the application you are using the ign switch power for. Relay closes with 12V, opens when 12V removed.
Click to expand...
Yes, I have a D4 260.

That is exactly what I needed to know!

Thanks for your quick reply!!
 
Volvo highly advises against taking any appreciable power from the multilink harness as that network controls most of the engine interfaces and signals including shift/throttle etc... Volvo makes a relay harness that plugs into any open multilink hub and that relay can be used to switch or deliver power to devices like the Bennett ATP.

Volvo Penta 21427463-P01

The regular part number for it does run around $300, however over the years they have created LOTS of various part numbers designed for OEM builders (Tiara, Riviera, Rinker, etc), which typically can be found at much more reasonably prices from $20-$75 between retailers or ebay.

These typically don't come with the relay, but those are exceedingly cheap just about anywhere. Then you just need to install whichever other wires you need corresponding to the relay terminals.
 
Full_O_Fish said:
Volvo highly advises against taking any appreciable power from the multilink harness as that network controls most of the engine interfaces and signals including shift/throttle etc... Volvo makes a relay harness that plugs into any open multilink hub and that relay can be used to switch or deliver power to devices like the Bennett ATP.

Volvo Penta 21427463-P01

The regular part number for it does run around $300, however over the years they have created LOTS of various part numbers designed for OEM builders (Tiara, Riviera, Rinker, etc), which typically can be found at much more reasonably prices from $20-$75 between retailers or ebay.

These typically don't come with the relay, but those are exceedingly cheap just about anywhere. Then you just need to install whichever other wires you need corresponding to the relay terminals.
Click to expand...
Yes, I had read what you are mentioning regarding pulling power from the multilink. My plan is inline with what BB marine stated which is to 1. Have an engine on/off wire that the ATP will use to send a signal to the control box to lift up the trim tabs (no power needed) and then an Ignition on wire which will activate a separate relay that will provide power to the ATP from the trim tabs fuse box (pretty much what you are discussing above). Thanks for your input!!
 
Try this part number: Volvo Penta 21475508
It includes the relay..plug and play.
 
If you have the folding side seats in your cockpit, there are magnetic switches for the alarm light at each seat. They are powered by the VP ignition and can be tapped into for the trim tab on-off.
 
You can purchase a multi link plug harness from Great Lakes skipper part number 3886666 . The harness is made for several different boat manufactures. I only used the B+ and Ground wires. I then purchased a relay with mounting bracket from Napa under $10. Under $50.00 worked great powered the alarm system from the 12V fuse panel at helm thru the relay.
 
BB marine said:
You can purchase a multi link plug harness from Great Lakes skipper part number 3886666 . The harness is made for several different boat manufactures. I only used the B+ and Ground wires. I then purchased a relay with mounting bracket from Napa under $10. Under $50.00 worked great powered the alarm system from the 12V fuse panel at helm thru the relay.
Click to expand...
Awesome - thanks!
 
summer wind said:
If you have the folding side seats in your cockpit, there are magnetic switches for the alarm light at each seat. They are powered by the VP ignition and can be tapped into for the trim tab on-off.
Click to expand...
The C28 does not have seat alarms because the seats are in the cockpit. They do not flip out like the C30. That is a nice option on the C30!
 
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