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Alarm Oil Pressure Sender Outdrive Oil

ehlien

Regular Contributor
96 Baja with 454 merc IO
A co


96 Baja with 454 merc IO
A couple trouble shooting questions.

Ok I have an alarm buzzer that does not want to go off. It goes on when I turn on the ingnition key and never goes off. I suspect the float in the outdrive reservoir. What other alarm would come on before you start the boat and stay on? I have good oil pressure and it has a new temp gauge sender and is not overheating. I'm trying to isolate the circuits out one at a time. How can I test out the float alarm? Is it a naturally open or closed switch? If i disconnect the wiring to the float will it kill the alarm?
Secondly..where is the oil pressure alarm sensor located? What color is the wiring to it? If I disconnect this wire I assume I will kill that circuit?
Finally..the alarm itself. I assume that if i kill all those circuits it will kill the alarm.
Don't you just love electrical glitches!!!
Thanks all
 
"Ok went out today but coudl n

"Ok went out today but coudl not get that dam alarm to dies. It is a very low buzz however, almost like its a pre alarm for something . In the past when I have overheated it has been much louder.
I tried disconnecting the drive oil reservoir and even jumping that harness to make a full connection but it does not stop . I also disconnecet what I think is the oil pressure sender at the back of the engine by the coil and distributor but that did nothing. Of course I don't know if these are supposed to be normally opened or closed circuits.
Anybody out there have some experience here?"
 
"Your alarm may have malfuncti

"Your alarm may have malfunctioned and is now staying on. Tan w/blue stripe is used on my 4.3L. All of the sensors are switches on a parallel line that turn on the alarm. Any one of them can set it off. Don't know if they are N/O or N/C switches.

Look thru this diagram for the switches. It seems that the alarm (2 wires in/under the dash) has power to it and is turned on by them.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=821723965&ivar=images/CRU ISER/821723.965/3.png&inbr=2345&bnbr=4&bdesc=WIRING+HARNESS+AND+ELECTRICAL+COMPO NENTS"
 
Thanks Guy. I'm coming to

Thanks Guy. I'm coming to the same conclusion that it has to be the alarm buzzer itself but its a $60 part I don't want to replace then find out I wasted significant $$ so I'll try to figure out if the circuits are NO or NC first. If I can determine what any one of them is the rest should be the same. If a temp sender is NC (if?) I'm thinking they are all NC. Gotta love electrical glitches!!!
 
Go to an electronic parts stor

Go to an electronic parts store and tell them you need a 12 volt alarm buzzer or beeper.
 
"If you disconnect the wires

"If you disconnect the wires to the oil pressure alarm sensor, it will cause an alarm condition.
While this connector is off, try junoering the two contacts togather with a paper clip to see if that stops the alarm.
BTW... the alarm will sound with the ignition on but the engine not running since the oil pressure is zero."
 
I just finished wiring my engi

I just finished wiring my engine and if I remember correctly for the audio warning system the oil pressure switch and the reservoir sensor are N/C. The water temp sensor if you have one is N/O closing on the rise. All switches send ground to the buzzer. 12 volts is sent to the buzzer when the ignition is on. So when you turn your key off the 12v should have been taken away from the buzzer. If you hear a soft buzz after the key is off then you still have voltage being supplied to the buzzer. Normal operation should have the buzzer on until the oil pressure builds up and opens the sensor.
 
"Ok EJ so if the pessure sende

"Ok EJ so if the pessure sender is N/C then when the ignition is charged the alarm should be buzzing until the engine creates pressue. Since the buzzer doesn't go off for me but the oil gauge shows pressure, and if I jump the oil resevoir circuit closed, then the pressure sender for the alarm must not be opening under pressure thus bad. Make sense?

John"
 
"[b]<font color=""ff0000"">whe

"<font color=""ff0000"">when the ignition is charged the alarm should be buzzing until the engine creates pressue.</font>

Correct.


<font color=""ff0000"">Since the buzzer doesn't go off for me but the oil gauge shows pressure, and if I jump the oil resevoir circuit closed, then the pressure sender for the alarm must not be opening under pressure thus bad.</font>

Disconnect one wire from your reservoir, that will disable it from sounding any alarm. If you have a water temp sensor then disconnect that also. Turn the key on, the alarm should buzz picking up the ground from the closed oil pressure switch. If it doesn't then your switch is broken, you don't have 12v to the buzzer or you have a broken wire. If it does buzz, then when you turn the ignition off it should stop. If it doesn't then you still have voltage present at the buzzer. Some Piezo buzzers will still buzz through a voltage range like 8-12v for example.
}"
 
"Ok , I have basically done al

"Ok , I have basically done all that and the buzzer does go off when the ignition goes off however, the buzzer does not go off when pressure comes up on the engine. The buzzing does sound seem to be lower however its under a closed dash and I'm running open headers so the engine noise is loud. Its a 94 with original snder and buzzer so I'm thinking it more likely the sender not opening unless you coudl still get low buzzing with the cuircuit closed."
 
With the other alarm switches

With the other alarm switches still disconnected bring the engine up to pressure then disconnect the oil pressure switch wire at the oil pressure switch. If it shuts off then the switch is bad. If it doesn't then disconnect the ground lead at the buzzer. If it shuts off then there is a short in your wiring going to ground. If it still doesn't shut off then your buzzer is going to ground internally and will need to be replaced.
 
"Ok last question, because I w

"Ok last question, because I was mistaking the oil gauge sender with the oil pressure alarm sender/switch. Where abouts is the actual presure sender/switch located on a 454 motor?"
 
"Oil pressure switch - look on

"Oil pressure switch - look on the left side of the block, below the freeze plugs, maybe 6 inches forward of the plane locating the flywheel inspaction plate. some setups will use a TEE with the switch on one side and the sender on the other."
 
Left side looking towards the

Left side looking towards the rear of the boat below the water pump and fuel pump area?
 
left side of block...same side

left side of block...same side the throttle shaft hooks onto with a carb on top. it will be behind (aft of) the auto motor mounting bosses and below the line the freeze plugs make.
 
Got it..always better to have

Got it..always better to have and idea of where to look before you crawl into that deep dark hole they stick the motor down in and you can't see a thing in!
 
Ok what is the knock sensor an

Ok what is the knock sensor and where is it located? Does it have a wire attached to it and if so what color?

What color wire is attached to the pressure switch?

I have located one or the other on the lower block between aft of the motor mount and before the starter but I am not sure which is which. It appears to have a solid blue wire attached to it.

Sorry to be a pest!!
John
 
The alarm pressure switch is u

The alarm pressure switch is usually a tan wire with a blue stripe. And the pressure switch for the instruments is usually a lite blue.
 
I have a new pressure sender s

I have a new pressure sender switch per the parts breakdown and chart posted previously and I believe it should go into the block just above the drain cock which is behind the motor mount and in front of the starter just above teh frost plug line but what is in block there right now looks a lot more like the knock sensor as per the parts drawings when you blow it up and it looks like a dark blue wire going to it. Is this the right location for the alarm sender? If so perhaps whats there is wrong. Is there a wire connected to knock sensor and what does a knock sensor do? Are there typically any other sensors or senders on the block in that area??
 
"John

Wrong Side - you [b]a


"John

Wrong Side - you are looking at the knock sensor!

look above the oil filter, if on the block, or where the remote adapter takes oil to/from the block. This PDF should help - it has the filter on the block

<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/mime_pdf.gif""" align=left alt=""application/pdf"">opswitch
[url=""][b]op switch.pdf[/b][/url] (25.3 k)</td></tr></table></center>

The knock sensor detects engine knock. the computer uses this to control the timing advance."
 
Ok but I think I'm getting

Ok but I think I'm getting some conflicting advice on location etc. I will check out the other side by the remote oil filter. I'm not sure this engine should even have a knock sensor though. Its a 1994 boat although the block is newer but its a distributor boat and I don't think there is any computer module to control advance. Its all old school I think.
 
"The PDF posted above is from

"The PDF posted above is from the factory manual.

Having the knock sensor installed won't hurt anything. The computer controlled engines can have distributors, too. Some - like the Thunderbolt-V distributors - have a knock control module bolted right to them.

As alluded to in some of the earlier posts, you can use the color of the wire connected to a switch or sender to determine its function.

TAN wire with BLUE trace - audio warning system; includes oil pressure SWITCH and overheat SWITCH (and low gear oil (newer MCM) or gear overheat on a MIE).

TAN wire - temperature SENDER to gauge.

LIGHT BLUE wire - oil pressure SENDER to gauge.

Also, a BLUE wire is shown connecting the Knock Sensor to its module."
 
"Ok
I checked the other side


"Ok
I checked the other side of the engine where the remote oil filter is located. It is mounted on a cast bracket on the top front of the port ehaust masnifold housing( left side facing the front of the boat right facing aft) there is no take off here for an existing pressure switch. The problem with finding anything on that side of the engine is extreme lack of visibility and accessibility. I can't hardly see or get to anything so I really need to narrow down best i can where to even look. Beyond the manifold that side has the hoses and oil cooler, power steering etc., It took me a day and half just to get the drain cock on the block removed and replaced last fall. welcome to boating..this would all take about 15 minutes on most cars.
angry.gif
"
 
Yeah! Not the remote oil filte

Yeah! Not the remote oil filter but the FILTER ADAPTER.

Follow the hoses from the remote oil FILTER back to where they connect to the ADAPTER on the ENGINE BLOCK.

Same region when you were around the starter but on the Other side.
 
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