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OK now for a weird question

C

captal

Contributing Member
"I have a 1989 Luhrs Tournamen

"I have a 1989 Luhrs Tournament 29, twin 270hp Crusaders, FWC. (Well that's no so weird since gas came down a little) but now the weird part. On the factory dash panel, the one with the various switches and engraved labels underneath. I have one switch that is labeled "Start". It is a center off, momentary up and momentary down. I have absolutely no clue what this switch is for. I have regular key start switches for the engines and I do not have a gen set. I've tried to trace the wires but they go down with all the other wires to the black hole. I can sit quiet and listen as I switch it up and down but can't hear anything run anywhere. Hope I didn't drop a depth charge or something. Any ideas fellas???"
 
"Just a guess here, but it cou

"Just a guess here, but it could be a "parallel start switch". It's used to start an engine who's dedicated batt. is too weak to crank the engine. This switch connects the other batt. to the opposite engine in order to accomplish a start."
 
"That sounds about right.

W

"That sounds about right.

With the 3 position switch, your system should be set up to connect (either one of) the engine start battery with the house battery momentarily, via 1 of 2 solenoids, for starting that slow cranking engine.
You should hear 1 of 2 similar solenoids click down in the engine room depending on the position you actuate the switch to.
You'll have to play with it to find out for sure, what position connects what battery banks.

Fred 156-M"
 
"Al,
I like your idea better

"Al,
I like your idea better BUT it may have been used for something and so many years later those leads may just terminate in air.

I had about 200 feet of such wiring on our boat"
 
"CAPT AL:

Sounds like a bat

"CAPT AL:

Sounds like a battery bridging circuit as Fred described. If still connected, it may be wired to need a key to "ON" before it may activate anything. If you really need the answer, get your HIN info and contact the OEM directly:
http://www.luhrs.com/index/ContactUs.html

I've contacted them a few times working on others' boats and they have been pretty good about getting answers out. No recent ownership changes so no reason for the policy to have changed."
 
"Good ideas guys but here is a

"Good ideas guys but here is a little more info. The batteries go through dual batttery switches, no relay switching there. Thought it might have something to do with the bilge blowers but they have their own switches. The wires coming from the switch are red/purple stripe and green/purple stripe. Thanks Mark. I'm sending Luhrs an e-mail to see if the have anything. Still open to ideas though!!!"
 
"Al:

you only have two wire

"Al:

you only have two wires coming off the switch?

how many terminals on the switch, 2 or 3?

The color codes aren't ABYC standard...Have you measured to see if they connect to +12VDC, GND, Etc?"
 
OK I might have said it wrong.

OK I might have said it wrong. It has two wires LEAVING the switch. A center red 12volt. I put a meter across the hot and load and flipped the switch but the meter didn't change. My guess is they are not connected to anything. I did e-mail Luhrs and just waiting for a reply. I'll keep ya'll posted!!
 
"Al
1) Do you have 3 batt

"Al
1) Do you have 3 battery banks
(<font color=""ff0000"">Port Engine,</font> <font color=""0000ff"">Starboard Engine,</font> & <font color=""aa00aa"">House</font>) & 2 (Off, 1, 2, both) switches ?

2) Do you understand what the purpose of the switch was for?

Fred 156-M"
 
"AL:

not sure what you are

"AL:

not sure what you are calling "load"....??

Alot of times, the terminal on the 'opposite' end of the lever is connected to the common (center) terminal, may want to recheck both terminals in both momentary positions."
 
"Fred: Yes I do have 3 batteri

"Fred: Yes I do have 3 batteries. I have 2 battery switches 1,2,both,off. I can see all the battery cables right to the engines. No solenoids in-line. I do remember the load sharing solenoid system but that's not what I have. Might have been years ago, not sure. Mark: I have 12volts going to the center of a 3 terminal switch. And yes the contacts are opposite the switch throw. If I put a meter on the hot lead and the other side to the wire leaving the switch (load) I get no voltage drop that you would expect to have with a device being powered. Still a mystery. Hope Luhrs can shed some light!"
 
"CaptAl:

I wouldn't exp

"CaptAl:

I wouldn't expect a significant drop across a switch, unless the load is significant. If you have a good meter, you can undo one lead from the switch and see if any current flows thru the switch. If no current is flowing, then what ever the switch controlled is either gone or disconnected."
 
"Big Al
1) If I had a com

"Big Al
1) If I had a common 3 position switch SPDT
(Momentary On - OFF - Momentary On) as you described, with a 12 volt power lead to the center term, with the outer terms hooked up to any kind of loads, (light bulbs, Solenoid, pump, ect.).

...A) "If I put (the + side probe of) a meter on the hot lead (<font color=""ff0000"">center</font>) and the other side (the - side probe) to the wire leaving the switch (load)",--- I would expect a 100% voltage drop (meter reads 12 Volt)
...B) As soon as I actuate the switch to energize either of the circuits,--- I would expect a 0% voltage drop (meter reads 0 Volt).
NOTE: Under extremely heavy, momentary loads, a 1/10 of a volt drop (meter reads 1/10 volt) may be acceptable.

2) If I had a common 3 position switch SPDT
(Momentary On - OFF - Momentary On) as you described, with a 12 volt power lead to the center term, with the outer terms NOT
hooked up to any kind of loads, (light bulbs, Solenoid, pump, ect.).

...C) "If I put (the + side probe of) a meter on the hot lead (<font color=""ff0000"">center</font>) and the other side (the - side probe) to the wire leaving the switch (load)",--- I would expect the meter to read 0 Volt
...D) As soon as I actuate the switch to energize either of the circuits,--- I would still expect the meter to read 0 Volt, as the is no return path provided for the flow of electrons, in both scenarios C, & D.

Fred 156-M"
 
"Pretty good description Fred!

"Pretty good description Fred!

I'd like to add one caveat; an 'open load' (burnt out light or pump, as examples) will behave just like the No Load case. It can be fustrating when troubleshooting, just something to remember."
 
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