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2008 Sundeck SD195 Wiring Schematic / Wiring Diagram

I'd like to get the complete wiring diagram for this vessel.  Currently trying to determine why the auto bilge isn't working (manual bilge functions correctly).  Soon I'd like to add a wash down station and plan to use the unused factory galley pump wiring and switch for that.


  • kstahl
    kstahl Member Posts: 6
    Update - I'm still hoping to get the wiring diagram for this vessel, but my UltimaSwitch auto bilge switch appears to be defective.

    More details - I did find a blown 4A fuse at the battery (brown wire with red tracer).  After replacing the fuse, I have power to the 3 pin deutsch receptacle feeding the UltimaSwitch and bilge pump.  With the UltimaSwitch submerged it doesn't operate the pump.  Since the wires and splice appear to be good and the pump functions from the manual helm switch, I'm assuming the UltimaSwitch is bad.

    My Concerns:
    • I see a potential issue with the wiring but would love to see the factory wiring diagram to confirm it.  My vessel has two batteries and a dual battery switch (OFF/ BAT 1/BAT 2/BOTH ).  The brown/red auto bilge circuit is permanently connected to one battery.  The rest of the vessel is selectable from the dual battery switch INCLUDING THE MANUAL BILGE CIRCUIT.  This doesn't follow the recommend wiring for the pump/switch and I believe it creates scenarios that could take out the auto bilge fuse and perhaps the UltimaSwitch itself.
    • Here is a scenario to consider:  Auto bilge is tied to battery 1, dual battery switch has battery 2 selected, manual bilge switch on, UltimaSwitch is submerged.  You are effectively connecting both batteries through a 4/5A fuse and the Ultima Switch.  At first this might seem like an unlikely scenario but not really.  It's very common to jump in a vessel, start going and have water run to the aft of the boat and activate the auto bilge circuit.  Many of us know the auto bilge doesn't get all the water out so we turn on the manual bilge to remove as much as possible.  In my opinion, this scenario could easily take out the fuse and may likely exceed the 20A rating of the UltimaSwitch for a short time until the fuse blows.
    • Based on the manufacturers manual, if the UltimaSwitch wiring is reversed the pump will run continuously.  This implies the UltimaSwitch doesn't have reverse polarity protection.  If that's true additional scenarios exist even when the switch isn't submerged.
    • Based on the manufacturers manual, the switch manufacturer recommends the UltimaSwitch be wired to a SPDT On-On switch.  This eliminates the possibility of both the manual and auto circuit feeding the pump simultaneously and eliminates the concerns mentioned (see image below).
    I'm contemplating a couple different fixes for this, but would like to review the factory wiring diagram first to make sure I'm not missing anything.
    1. Install two diodes.  This is probably the simplest solution (no additional wires to run).  However it creates a voltage drop to the pump and some heat.  Also I can see where it might be frowned upon in terms of safety, etc.
    2. Replace the SPST On-Off helm switch with a DPDT On-On switch.  In the down position one pole would connect the fused brown/red circuit with the brown/white of the Ultima switch.  In the up position the other pole would connect the existing manual bilge wires.  The downside is that if the manual helm switch is on it disables the auto bilge feature.
    3. Replace the SPST On-Off helm switch with a SPDT On-On switch (like the manufacturer recommends).  In the down position it would connect the fused brown/red circuit with the brown/white of the Ultima switch.  In the up position it would connect the fused brown/red circuit with the brown bilge pump wiring.  The downside (to me anyway) is that the manual bilge switch would no longer be controlled by the master switch or dual battery switch.  Also if you blow the 4/5A fuse you lose both auto bilge capability AND manual bilge capability.
    4. Have the manual bilge switch operate a SPDT relay.  This seems like the best solution to me.  It would retain all the current features and should prevent the problems.  If I place it in the aft minimal wiring is needed.  My vessel has good access to that area through an interior access panel.
  • kstahl
    kstahl Member Posts: 6
    edited July 2023
    I've determined that both my 5A fuse and my UltimaSwitch auto bilge switch are bad.  It seems to me there might be a potential problem with my boats wiring.  Hopefully the factory wiring diagram will help me understand if my concern is valid. 

    Here is a scenario to ponder: You have a dual battery system.  Your auto bilge is permanently connected to battery 1 and your dual battery switch has battery 2 selected.  You jump in your vessel and go.  Water runs to the aft of the boat and activates your auto bilge.  Noticing this you turn on your manual bilge helm switch to get all of the water out.  The way my boat is wired this scenario effectively connects the two batteries together via the fused auto bilge circuit, UltimaSwitch and manual bilge circuits.

    It seems to me the scenario described above could easily take out the fuse and in the short time before the fuse blows may easily exceed the 20A rating of the UltimaSwitch.  Reading the manufacturers manual for the pump/switch it recommends different wiring that would prevent this from happening.  The manual also mentions that if the pump runs continuously the UltimaSwitch wiring could be reversed.  This implies the UltimaSwitch doesn't have reverse polarity protection.  This creates even more likely scenarios for this to occur.  Especially since the UltimaSwitch wouldn't need to be active (submerged).

    I'd still like to confirm my wiring matches the factory wiring diagram.  If it does, I think I'm going to install a relay to prevent this possibility in the future.
  • kstahl
    kstahl Member Posts: 6
    edited July 2023
    My replacement Ultima Switch arrived and I did a little bench testing with it.  As the manual states if the Ultima Switch is wired in reverse it runs the bilge continuously.  With the switch wired correctly this actually creates another more likely scenario: Your boat is moored and your auto bilge has significantly drained one battery.  You use the dual battery switch to select the opposite battery to fire up and you turn on the manual bilge to get the remaining water out of the hull.  Because the Ultima Switch conducts in reverse, the moment you turn on the manual bilge you are trying to charge the drained battery through the bilge circuit!  A drained lead acid battery could easily draw 20A or more.  This would easily take out the fuse and might take out the switch.

    My suspicion is that people with blown auto bilge fuses or bad auto bilge switches probably have dual battery setups where the auto bilge circuit is dedicated to one battery and the manual bilge circuit is selected by the dual battery switch.

    Other findings/comments:
    • The Ultima Switch appears to have a negligible parasitic draw.  Using a basic ammeter, it seems to fluctuate between 6 microamps (0.000006A) and then "wake up" and draw 25 microamps (0.000025A) for a short time.  The "wake up" likely coincides with the 3 second start delay mentioned in the documentation.  With such a low level of draw, it's safe to say this device will never drain your battery.
    • According to Littlefuse, a 5A fuse will allow 20A for about 0.1 seconds before it blows.  Whether or not it is possible to damage the switch in that amount of time is unknown.
    • A DC motor is an inductive load.  Switching inductive loads can be pretty hard for electronics.  The Ultima Switches lack of reverse polarity protection is probably by design since this would act like a reverse bias diode (aka flyback diode) and quench the back EMF generated by the motor.  However if the auto bilge fuse is blown and the pump is manually run, the blown fuse eliminates the path to quench the back EMF.  So where does that back EMF energy go?  Could the voltage spike generated by the back EMF have a harmful effect on the Ultima Switch?  Here is a video that demonstrates what can happen when you switch inductive loads:  Here is a video showing hundreds of volts of back EMF generated from the inductive load of a 5 volt relay coil:
    • The switch manufacturer has pretty specific instructions about how this device is to be wired (see image below).  They recommend running the auto and manual circuits off one battery and one fuse.  To me this eliminates all of the scenarios mentioned except for one.  If the fuse blows while the bilge motor is running there is no path to quench the back EMF.  This most certainly creates a voltage spike but I don't know where or how it gets dissipated.
    • While I think the bilge wiring circuit in my boat may have some flaws, it does have some advantages.  I like the fact that I have redundancy by having the manual bilge circuit separately fused.  I also like the fact that my master switch and dual battery switch control the manual bilge switch.  So the chance of having it left on or turned on by vandals (or grandkids) is way lower. 
    • My manual bilge helm switch is a SPST.  Without changing the switch to a SPDT, it's impossible to wire the switch as instructed by the manufacturer.
    • I've ordered a sealed automotive style relay.  This should give me all the features of the factory wiring but prevent the possibility of both the manual and auto bilge circuits from being connected simultaneously.  Since I'm not sure what happens to the back EMF when the auto bilge fuse blows, I'll probably add a reverse bias diode across the bilge motor leads to protect the Ultima Switch.
    Manufacturers recommended wiring for manual/auto operation: