Mystery Wire and Chirping Alarm

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gpd955

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Looking for some input to solve a mystery....

1. There's this wire that has been laying on top of the engine (Universal M25XPB in a Catalina 310) since I bought her. It's pictured below. The engine and instruments/gauges work fine but curiosity has got the best of me. It must be for something but I cannot find anything it connects to. It is orange or brown in color and comes out of a harness. The other wires that come from the harness are pink and lt blue (to alternator) and yellow (to water temp sender). Looking at the DC diagram for the engine and the boat itself I cannot figure this one out. Any suggestions? Pics are below.



2. My panel alarm is chirping. It's not a steady alarm and the volume of it varies as the engine vibrates and as i change throttle. Again, the engine runs fine and gauges indicate all is well. I can shut the key off and it will stop. I put a new oil sending switch in last year when a terminal broke off and the alarm sounded. Those connections are still intact. Nothing in the manual or troubleshooting guides address the chirping, just a steady sounding alarm. Will record the sound tomorrow when I head out.
 

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finding41

finding41

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Nov 23, 2011
2,023
MacGregor 26D London Ontario Canada
I know nothing about your boat but I get calls from customers to diagnose strange beeping or other noises in there homes. #1 noise is a smoke detector or carbon monoxide detector with a low battery. It is usually stuck in a cupboard. But check them all.
For $60 each visit, plus battery's, I come by and chance the battery's in someones smoke detector etc twice a year. Timing is when we change the clocks here.
Good luck.
 
Richard19068

Richard19068

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Jun 11, 2004
1,923
Oday 31 Redondo Beach
http://www.marinedieseldirect.com/universal/200157/universal-owners-wiring-diagram.html

If it is orange it could be the old wire from the alternator to the ammeter (#4 on the diagram) that has since been rewired to eliminate the excessively long run between the alternator and the battery.

Don't know about the chirp other than maybe a loose connection somewhere in the alarm circuit or maybe you got a faulty oil pressure sender when that was replaced. Did the chirping start around that time?
 
gpd955

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
As a former professional firefighter (and volunteer) I always check mine!! However it never ceases to amaze me when I answer calls and all I hear in the background is that chirping noise while I'm dealing with whatever it is I have to deal with! And people get annoyed when I suggest they change the battery!
 
Witzend

Witzend

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Dec 25, 2008
1,580
catalina 310 Elk River
Hey Jack,
I know the wire you're referring to, it connects to the stud for the coolant temp sensor right next to it in your first pic, (slides on at a 90deg. angle on the top of the stud). The sensor appears to already have a wire on it, may be the ground wire. I also believe that the alarm (which is really a 24 volt alarm running at 12v, poorly chosen for the application), should produce a solid on sound with low or no oil pressure (as when the engine is cold and the key switch is first turned on), or produce a pulsing sound when it is over temp. Because the alarm is working at under voltage already if your battery voltage is low, it will cause the alarm to be weak and intermittent.
 
gpd955

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Yeah. It was lying right next to the sensor but there is no place to connect it. Maybe the connection broke off. I have found that most of the wire connectors on this engine (e.g. Oil sending switch) are extremely delicate. The yellow wire (which is on the sensor) is definitely correct according to the manual. Everything runs fine but it's one of those things that will be constantly on my mind!
 
Witzend

Witzend

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Dec 25, 2008
1,580
catalina 310 Elk River
No, it is not broken off, just slide it on at a 90deg angle to the top of stud. We had a great raft up on the Chessy this weekend with (4) 310s, and one of the other 310s also had it disconnected, but did not notice any alarm problems? I reconnected it for him...poor design.
 
gpd955

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Like that?? Looking at the terminal on the wire, that's the only way it would work.

We were considering coming down for that raft up but had hockey school in Lake Placid. Good to hear it was fun!
 

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gpd955

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Now my engine won't turn over. I disconnected it and it still won't turn over. It never ends!
 
joker460

joker460

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Apr 27, 2010
970
Beneteau 352 Hull #276 Ontario
If you have an ohm meter, measure the resistance of the sensor just to make sure it's not shorted. Maybe that's why it was disconnected?

Good Luck
 
Witzend

Witzend

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Dec 25, 2008
1,580
catalina 310 Elk River
They should not even be related, but if it were shorted, check the the reset button on the engine.
 
Witzend

Witzend

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Dec 25, 2008
1,580
catalina 310 Elk River
It is called out as the" Water Temperature Alarm" on the M25XPB break drawing for the fresh water cooling.
 
gpd955

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Witzend said:
They should not even be related, but if it were shorted, check the the reset button on the engine.
Click to expand
Already did that. Still had power to the panel though. I will do some diagnostics after dinner!
 
Witzend

Witzend

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Dec 25, 2008
1,580
catalina 310 Elk River
In reviewing the schematic this is a hi temp switch that shorts to ground when a threshold temp is reached and sounds the alarm. So with it disconnected it should just not be able to sound the alarm if over temp, which would not be the reason you are chirping. Can't imagine it could prevent the engine from cranking.
 

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Witzend

Witzend

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Dec 25, 2008
1,580
catalina 310 Elk River
I found a pic of my engine. I had you have it connected to the wrong sensor. It actually connects to the one on the other side of the housing see pic.
Sorry for mis-leading you, I became confused between the two just looking at the pics.
 

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gpd955

gpd955

.
Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Witzend said:
I found a pic of my engine. I had you have it connected to the wrong sensor. It actually connects to the one on the other side of the housing see pic.
Sorry for mis-leading you, I became confused between the two just looking at the pics.
Click to expand
I will reconnect it to te proper place. Thanks for sending that. Makes it easier!
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,760
Canadian Sailcraft 36T Casco Bay, ME
Witzend said:
Hey Jack,
I know the wire you're referring to, it connects to the stud for the coolant temp sensor right next to it in your first pic, (slides on at a 90deg. angle on the top of the stud).
Click to expand
Bingo, but it goes on the opposite side of the t-stat housing..Here's a pic...
 
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