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2003 RLXI Alarms and Oil Pressure Gauge Dips


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Recently brought home a 2003 RLXI with a Monsoon 335 and was very happy, until the maiden voyage.  On first high speed run, the boat began to emit an alternating beep.  All gauges are in normal ranges.  (The gauge cluster includes a large four parameter gauge including oil pressure, temp, fuel, and voltage,  a large gauge for MPH with a rectangular digital display, and another large gauge for RPM.  No perfect pass or other speed control).  No unusual sounds or other indications from the engine.  If the engine is turned off and restarted, the alarm goes away and runs normally until some period of time later the alarm will again start beeping again with no indication of what is causing the problem.  This occurred 3 times in 30 minutes with no particular rhyme or reason until I parked it.  Perhaps it is completely coincidental, but two of the three alarms occurred when making sharp turns.

Also noticed that occasionally the oil pressure gauge will drop to zero and within a second or two it will jump back to full pressure of 50 to 60 psi.  This does not appear to trigger the beeping alarm mentioned above.  The boat seems to ignore this when it happens.

Previous owner indicated that the oil pressure gauge had been temperamental recently and the sending unit was replaced and certainly it appears to be shiny and new.

Any ideas or hints of where to start to resolve these issues would be helpful!

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16 hours ago, Virginiaray said:

Previous owner indicated that the oil pressure gauge had been temperamental recently and the sending unit was replaced and certainly it appears to be shiny and new.

There are 2 oil pressure sending units, one for the gauge and one for the alarm.

Edited by MadMan
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ahopkinsVTX

Friend had similar alarm symptoms on his 99 SSlxi. Turned out the be a bad knock sensor. He first replaced both oil pressure sensors and it still continued. He finally tracked it down to a knock sensor. I’d try the oil pressure sensors first but if it continues maybe try replacing the knock sensors. 

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Another post I saw suggested disconnecting the sending unit and the alarm should stop if that is what is causing it.  Removed each of the wires for 10 to 15 seconds during alarm and the alarm persisted.  

Suggestions on where to find the knock sensor and what it looks like?  Should I try disconnecting it during an alarm also to see if the alarm stops?

Any suggesting for finding a wiring schematic for this boat?

Tried to check the connections on the gauges but don't see how to access the back of the gauges.  Do I have to pull the entire gauge cluster out of the dash?  Gauges shown below.

 

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Knock sensor looks like this

https://www.skidim.com/prodinfo.asp?number=R020027

Its on the bottom of the block, can't remember if its on boh sides or just one back then. They do corrode away, so need replacing at least every few years.

As for the dash, two screws in the malibu emblem and the one dead center at the top, and it should slide right out, nice and easy. But i doubt that is the issue. 

 

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Gauges aren't your problem.  You don't have to bother with that.  I would look for ground issues for the oil sending units and swap out the knock sensor as mentioned already.  Though I've never seen one of those corrode to the point of going bad.

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3 hours ago, UWSkier said:

Gauges aren't your problem.  You don't have to bother with that.  I would look for ground issues for the oil sending units and swap out the knock sensor as mentioned already.  Though I've never seen one of those corrode to the point of going bad.

In our Lxi the first one i took out was in by about 1 thread and had a big pit in the middle. I suspect it was the original, that was back in the fall of 2015. This fall i took it out, and it was somewhat corroded, so i just replaced it.

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As stated gauges are not your issue, unless one of them is reading out of whack   

Knock sensor is a possibility as is the oil alarm sending unit (2 different units as mentioned before).  Big round one is for the gauge.  Small round one is for the ECM. I have had both go bad on my 2002 sunscape.  Knock sensor does not cause the alarm  unless your over 3000rpm if my memory is correct.  If oil pressure unit is going and intermittently failing it seems to show up at idle once the engine is warm.  

Intermittent ground could be the culprit too.  Both oil sending unit ground to the block through the threads  make sure the threads are clean and no Teflon tape or sealant on them 

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Not to nitpick, but it is a "sender unit" to dash gauge and a 6psi pressure sensor (on/off) that triggers beeping.  My oil pressure sending unit started to do exactly as yours did before I replaced it.  Cheap and fast fix. 

Anyway, I would check oil and trans fluid levels for sure and as previously mentioned change the knock sensor before going any deeper.

BEEP CODES — the 4 maintenance items that can trigger the beeper are:

  •  High engine water temperature (>203*)
  •  Low oil pressure (<6 PSI)
  •  High transmission temperature (>140?*)
  •  A diagnostics trouble code
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Thanks for all the hints.  Both of the sending units appear to have Teflon tape on them.  Should I use pipe dope or nothing hoping the tapered pipe seals?

The oil pressure gauge is becoming more temperamental as time goes on.  Stays on 0 PSI more frequently.  I'll check the grounding then don't know where to look.

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Update:  Found a marine mechanic with scanner.  Confirmed knock sensor error.  Replaced knock sensor and connector.  After 1.5 hrs running, NO ALARMS!!!

Getting better.  Bad thing is that the oil pressure and now the temperature gauges are both intermittently going to zero and other assorted variations on that theme.  No discernible pattern to it.  Tightened the connection on the oil p sender unit but didn't change it.  Haven't cleaned the threads, but that seems like stretch.  Is there something that would be common to both the temperature and oil pressure gauges.  Checked the connector on the back of the gauges and it is clean and dry.  Makes me nervous driving around with 0 psi oil pressure!

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Swap the connectors around - like from working tack to 4-1 gauge.  The (M)MDC uses a bus-type wiring so any wire can go to any gauge.  And break out your wallet...

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Like Eagleboy99 said you can swap the connections on the gauges - if you have Perfect Pass you will have a spare connector hanging back there.   And make sure the connector snaps when you put it in - it could be that it's just not in tight enough. 

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54 minutes ago, Virginiaray said:

oil pressure and now the temperature gauges are both intermittently going to zero

Water to zero is no biggie but if oil goes to zero - for real - that is a biggie.  But I'm guessing that the gauge reads zero when there is still good pressure.  Which is sensor/gauge/wiring.  An alarm should go off if oil goes to zero for any length of time.

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Update: Removed and reinstalled the gauge oil sender unit and added a separate ground wire using a hose clamp around the body of the sender just to make sure it was well grounded.  Also spent a couple hours inspecting and cleaning all ground connections I could find on the motor.  Then ran the boat for about an hour and noticed not gauge problems at all, EXCEPT the oil pressure would still occasionally go to zero and be very slow to build to 40 PSI+.  I am starting to think it is time to replace the oil sender unit just to at least eliminate that as an issue.  Anyone recommend one I can order for this 335 Monsoon?

 

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Double check and clean your cannon plug connections.  Only 5 volts at milliamps goes thru that connector for gauges.

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5 volts is typical for microprocessor driven instruments.  Current range is only 4 to 20 milliamps.  That is why clean and sound connections are a must.

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30 minutes ago, electricjohn said:

5 volts is typical for microprocessor driven instruments.  Current range is only 4 to 20 milliamps.  That is why clean and sound connections are a must.

And don't forget to clean the ground connections at the rear of both heads.  As @Bozboatdiscovered, the fuel tank ground isn't always connected where the other grounds are.  Look around and clean and tighten all you can find. 

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