Second Circuit Powered When First Circuit Energized

Electrical and electronic topics for small boats
floater
Posts: 172
Joined: Sat Oct 24, 2015 3:55 pm

Second Circuit Powered When First Circuit Energized

Postby floater » Fri Jul 02, 2021 6:06 am

I have a 1988 Boston Whaler Revenge 20 WT. It has the original Boston Whaler Bilge Pump switch. I installed Lenco Trim Tabs about 2019. I didn't have any electrical problem until 2021.

I updated the original fuse block with a [Blue Sea Systems brand] 12-circuit secondary power distribution fuse panel. The were no electrical problems following this change.


Now in 2021, when the main key switch is in the OFF position and the electric sump pump switched is ON, the Lenco Trim tabs power on and off.

The power distribution branch circuits for the Bilge Pump and the Trim Tabs are separate, but both originate from the [Blue Sea Systems] panel.

I replaced the original bilge pump switch with a two-way rocker switch. The behavior of the trim tabs did not chance same.

I reinstalled the original Bilge Pump switch.

When I disconnect the Bilge Pump from the power distribution panel. the Trim Tabs will not work.

I traced all wires and found no short circuits or broken wires.

I put a test light on the negative side of the bilge pump wiring, at the fuse panel, and it lights when I turn on the bilge pump. No other circuit does that.

I'm stumped.

Has the [Blue Sea Systems] fuse panel failed in some way?

On July 1,2021 I will wire the bilge pump directly to the battery and see if that makes a difference.

Lastly, when I disconnect the negative cable from the battery, with all power systems in the off position, and reconnect it there is a large spark. This seems to me there is a dead short some where.

Give me suggestions on a remedy [to the problem of the effect of the bulge pump circuit causing the trim tab circuit to power on and off when the bulge pump is energized].

jimh
Posts: 11670
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Second Circuit Powered When First Circuit Energized

Postby jimh » Fri Jul 02, 2021 7:15 am

Remove the fuse for the branch circuit that powers the sump pump.

Does the trim tab circuit still work normally?

floater
Posts: 172
Joined: Sat Oct 24, 2015 3:55 pm

Re: Second Circuit Powered When First Circuit Energized

Postby floater » Fri Jul 02, 2021 5:15 pm

I removed the fuse for the bilge pump and the trim tabs stopped working with the key on. The tabs also didn't cycle on and off when I pushed the bilge pump switch. I traced all wires today and found no corroded or split wires. I wired the bilge pump right to the battery and it no longer cycles the trim tabs. I think something in the Blue Seas Fuse block may have failed. I am going to remove the Blue Seas Fuse block this week and take it apart. I will likely replace it anyways and post back my results. Thanks

jimh
Posts: 11670
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Second Circuit Powered When First Circuit Energized

Postby jimh » Sat Jul 03, 2021 8:48 am

Based on the last report, power to the trim tabs is being supplied by the same branch circuit that powers the sump pump.

Electrical current’s behavior is very consistent. For this to happen there must be a direct wire connection.

A careful visual inspection should find the connection.

floater
Posts: 172
Joined: Sat Oct 24, 2015 3:55 pm

Re: Second Circuit Powered When First Circuit Energized

Postby floater » Sun Jul 04, 2021 7:23 pm

There are no wire connections between the two systems. The only thing they share is the Fuse Block but on different circuits. The odd behavior appears to have resolved itself. No idea how.

The only thing I can think of is the orange trigger wire, that retracts the tabs when ignition power is off, may have gotten some water in it after the boat was drenched in a big rain storm while fishing earlier in the year. This orange wire is attached to an ignition source off of one of the gauges. I will be rerouting this wire to a spot where no water may get to it again.

Thanks for the help

jimh
Posts: 11670
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Second Circuit Powered When First Circuit Energized

Postby jimh » Fri Jul 09, 2021 8:45 am

Based on the description of the “orange wire”, I infer that the tab control systems senses a transition of voltage on the orange wire circuit to 0-Volts from 12-Volts as a signal to raise the trim tabs to the full-up position.

As I am not familiar with the control system, I must ask: what action is supposed to occur when the orange wire circuit sees a transition to 12-Volts from 0-Volts?

If such a transition is supposed to initiate some movement of the trim tabs, then perhaps the previously described “cycling” of the trim tabs could be explained by some unexpected input from the orange wire to the control module.

Generally if two conductors are close to each other for a long distance, it is possible to a large change in current flow in one conductor to induce a small change in current flow in the other conductor, even though there is no direct connection between the two. If the orange wire circuit is a high-impedance voltage-sensing input, it could be fooled by such an induced current.

floater
Posts: 172
Joined: Sat Oct 24, 2015 3:55 pm

Re: Second Circuit Powered When First Circuit Energized

Postby floater » Fri Jul 09, 2021 4:17 pm

The orange wire is called the Retractor Circuit. It's attached to a 12 volt Ignition source. When you turn off the engine ignition the loss of 12 volts causes the actuators to pull up the trim tabs so that they are not in the down position when the boat is not in use. Both the bilge wiring and the trim tab wiring is nowhere near each other. I have another dual switch for the panel now and if the problem arises again i will swap out the switch and see if that solves the concern.

floater
Posts: 172
Joined: Sat Oct 24, 2015 3:55 pm

Re: Second Circuit Powered When First Circuit Energized

Postby floater » Fri Jul 09, 2021 4:21 pm

I'm not sure what the Retractor Circuit does when it senses 12 volts. I'm guessing it cycles the lights on the double rocker switch. When I was having the problem the lights on the rocker switch and the actuators were both cycling.