Warning buzzer going off above 40 mph on 03 Wakesetter VLX

[rm32644]

This spring, the warning buzzer is going off, if I drive the boat at 40 mph or more, and it won't go off unless I stop the boat and turn the engine off. All of the gauges are reading normal numbers, oil pressure 10 to 50, depending on the speed, normally 40 when cruising, temperature constant at 160, battery 13.8 volts, (14.3 with digital meter check), gas tank near full. The engine is running great. I can drive for hours at 25 mph, no buzzer. 478 hours. All 3 fluid levels are within dipstick range. Any ideas?

This is the Malibu Monsoon 5.7L fuel injected engine. 325 HP.

Side note: I had starter problems with the stock starter system until I installed a 30 amp output, 0.5 amp signal relay between the ignition key and starter solenoid. That's been fine now for 4 years.

[wakebrdr94]

I'm not sure by any means, but I had a similar incident years ago only 02 vlx. I took it to the dealer, and although the gauge read fine, they said it was had something to do with the oil pressure. Nthey fixed it and never heard from it again as long as I owned the boat

[MalibuNation]

RPMs?

[nemalibu]

Not sure but it sounds similar to when my "low oil pressure sensor" went on my 03 Monsoon. Pressure read fine but this is a seperate sensor mounted in the same area. Diagnosed by pulling the wire off of the sensor - no more warning buzzer. Replaced sensor - roughly $10 part (plus cost of high temp thread sealant) - and all was fine from then on.

[grandude]

It is your oil pressure switch. If you look down where your oil filter is located you will see two sending units. One is about 3 times larger than the other. The bigger one will be mounted length wise on the engine while the smaller one is facing out. The smaller one is the one you need to replace. If you want to test it first to verify, run the boat and set off the alarm. Then unplug the wire to the sending unit and try to set it off again. Be very careful when you go to change it to hold the manifold still that it is mounted to. Both sensors are mounted to a brass manifold that is attached to the engine via a 1/4 brass nipple. It is very easy to get enthusiastic when changing the switch and not hold the manifold still. It breaks very easily, trust me.

I would pull the part and take it with me to the parts store and let them match it up.

[rm32644]

RPMs?

The rpms are almost identical to the speed, ie: at 40 mph it is 4000, all the way up to top speed of about 55 mph and 5500 rpm. So I'd estimate that the buzzer comes on after 3 minutes around and above 4000 rpm. Not with just a spike above 4000 rpm.

[Web]

On my 03, the digital display would also flash OILP, that how I would know the sensor failed.

Also ck to make sure your wire to the knock sensor is hooked up.

[rm32644]

It is your oil pressure switch.

I just went down to my dock, to look at the area you described, and it is exactly as you described. I can see that I need to put a small crescent wrench on that brass tee manifold when I loosen the small sensor, to react the torque. I will try your test procedure next. I wonder exactly how the pressure sensor is failing, high oil pressure grounds an internal switch? I'm not aware that it is supposed to warn for high pressure, just low pressure. So somehow, high pressure is activating a low pressure sensor.

So far I am very impressed with the tech knowledge on this website, plus the number of responses already. I am coming to the conclusion that forums are often more useful than service manuals.

Edited May 27, 2013 by rm32644

[rm32644]

On my 03, the digital display would also flash OILP, that how I would know the sensor failed.

Also ck to make sure your wire to the knock sensor is hooked up.

Do you know where the knock sensor is located?

[Web]

Port side. The knock sensor is the block drain on port side. Should have a blue wire that snaps on the end.

[LUV2SKI]

Do you know where the knock sensor is located?

If you look at the your Indmar Marine Engines Manual on page 1-2 it will show you a picture and location. Or you can go to the top of this forum and under resources, click on your boat in malibu specifications and look at the engine manual.

[rm32644]

If you look at the your Indmar Marine Engines Manual on page 1-2 it will show you a picture and location. Or you can go to the top of this forum and under resources, click on your boat in malibu specifications and look at the engine manual.

I'm familiar with the that sensor since I take it out each fall to drain the port side engine water. I guess I should check it next, since the oil pressure sensor disconnected had no impact on the buzzer coming on above 40 mph.

It is your oil pressure switch. If you look down where your oil filter is located you will see two sending units. One is about 3 times larger than the other. The bigger one will be mounted length wise on the engine while the smaller one is facing out. The smaller one is the one you need to replace. If you want to test it first to verify, run the boat and set off the alarm. Then unplug the wire to the sending unit and try to set it off again. Be very careful when you go to change it to hold the manifold still that it is mounted to. Both sensors are mounted to a brass manifold that is attached to the engine via a 1/4 brass nipple. It is very easy to get enthusiastic when changing the switch and not hold the manifold still. It breaks very easily, trust me.

I would pull the part and take it with me to the parts store and let them match it up.

I ran the test and unplugging that wire had no impact on the warning buzzer. Still comes on by just driving faster than 40 mph with it unplugged. I unplugged the other pressure sensor wire, and I lost my engine oil pressure gauge, read zero, buzzer still on.

[electricjohn]

If your knock sensor is unplugged or bad, the alarm comes in above 3000 rpm and sets a trouble code in your ECM.

edit; after reading your post #6, it sounds to me like it is a tranny overheat issue. That will bring in an alarm, being there is a temperature sensor on the tranny connected to the ECM

Edited May 28, 2013 by electricjohn

[rm32644]

Thanks to all you guys who gave me instructions on stuff to try. Several of you mentioned the knock sensor, which I always thought was the engine temperature sensor, without researching it. I remove it every fall to drain the port side engine water, and then put it back in with the other plugs and add 2 quarts of pink antifreeze, to keep the impeller wet over the winter. So the boat is effectively de-winterized the same day. This fall I apparently forgot to reconnect that wire. I just did today, and that fixed the problem. This forum quickly saved me an expensive trip to the dealer, so I really appreciate everyones responses. I didn't have a clue what was going on before I got on this forum.

[Garry]

(2001 VLX Sunsetter, 5.7v EFI engine)

I had a similar issue after launching this spring.

Boat runs smooth in the yard, all gages normal, engine & trans cooling temp feel OK, oil in Eng/Trans/Vdrive all OK.

Get the boat on the lake and have no issues *unless* l exceeding 3000RPM.

As the RPM go over 3000, the buzzer goes off, and stays on at any speed, until I turn the key off

If I cycle the ignition (off, wait 5, then start) buzzer is off.

recheck all gages & fluids & touchtest cooling lines - all looks good & gages reading normal range

doublechecked Anti-knock sensor wire, it is connected (its still the original)

any suggestions?

[smooth as glass]

Boat runs smooth in the yard, all gages normal, engine & trans cooling temp feel OK, oil in Eng/Trans/Vdrive all OK.

Get the boat on the lake and have no issues *unless* l exceeding 3000RPM.

As the RPM go over 3000, the buzzer goes off, and stays on at any speed, until I turn the key off

If I cycle the ignition (off, wait 5, then start) buzzer is off.

recheck all gages & fluids & touchtest cooling lines - all looks good & gages reading normal range

doublechecked Anti-knock sensor wire, it is connected (its still the original)

any suggestions?

Exactly what I'm dealing with as well......Changed all but Tranny sensor. Guess it's next.

[Garry]

Found the issue. There are 2 sensors on the front of the motor

(its a Vdrive so the motor is backwards, if you are standing in the boat f- acing the transom (transmission at you feet, thermostat/pulleys in the back)

The sensor on the right - appears to be the temp guage

1. the sensor on the left goes into the INTAKE manifold, but looks like a O2 sensor. That sensor connection was very corroded when I removed the connection. cleaned It up, applied Dielectric grease, reconnected
2. I pulled the wire off the anti-knock sensor (one more time) and noticed it was abeit rusty. Also cleaned it up, applied dielectric grease, reconnected

I ran the boat for 1hour, all RPM range, and the buzzer no longer tripps. Im speculating its the first sensor, due to the corrosion on the connection, and I had previously reseated the anit-knock sensor several times.

Does anyone know what the sensor (#1 above) is / does?

it looks like a O2 sensor, but its going into the INTAKE manifold, and all other base sensors are accounted for.

[jeremyNJ]

It is your oil pressure switch. If you look down where your oil filter is located you will see two sending units. One is about 3 times larger than the other. The bigger one will be mounted length wise on the engine while the smaller one is facing out. The smaller one is the one you need to replace. If you want to test it first to verify, run the boat and set off the alarm. Then unplug the wire to the sending unit and try to set it off again. Be very careful when you go to change it to hold the manifold still that it is mounted to. Both sensors are mounted to a brass manifold that is attached to the engine via a 1/4 brass nipple. It is very easy to get enthusiastic when changing the switch and not hold the manifold still. It breaks very easily, trust me.

I would pull the part and take it with me to the parts store and let them match it up.

Great post. I am in the middle of trouble shooting alarm and found your post so decided to change. I saw your warning, but guess I kind of misinterpreted it and broke the thing anyway. I took nipple out and will hopefully have no problem putting everything back together.