"Check Engine" Alarm Troubleshooting Advice Please

Terry Olson

Chief Petty Officer
Joined
Aug 20, 2005
Messages
415
I'm running a 2004 Johnson 50 2 stroke on my 1994 Lund tiller boat. The VRO system is still in use. The engine warning system has four lights - "no oil", "water temp", "check engine", and "low oil". I'm experiencing a "check engine" light with steady warning alarm. The engine runs like it should (not in SLOW mode), seems to be using oil, and shows a strong telltale stream. I can't find any troubleshooting procedures. The owner's manual speaks to the oil and temp warning alarms but it says nothing about the check engine one. I see that some are equipped so that the fault code may be read, but I haven't found any way to do this with mine. Where do I start? I'll add that I've inspected the motor an I find nothing unusual visually.

Thanks in advance for your time and advice.

Terry
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,137
The Check Engine alarm was used on the '98 V6 motors and indicated a fuel restriction. It was not used on smaller motors in 1998. You will need to check an owners manual for your motor to see if the alarm is even used on your motor.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
A steady alarm is an overheat condition. The steady stream from the tell tale means little. Verify you are not overheating by placing your hand on top of the head while running. You should be able to hold it there. The check engine light could be as simple as a faulty system check guage. All those used the guage but not all motors use the check engine circuit of that guage.

I strongly suggest running on 50:1 premix in your tank while you diagnose a bad guage, warning horn, or whatever is causing the alarm. Double oil will hurt nothing. It's actually recommended for certain situations.
 

daselbee

Commander
Joined
Jan 20, 2009
Messages
2,765
No check engine function on that 50 hp engine. since the horn is controlled by the tach, it is very likely that the tach is bad.
Alternately, the tach has an 8 pin connector. If the line that would normally run back to the vacuum switch (on a V6)...if that line happens to be grounded, then the alarm will sound and the check engine light will light.
The wire color for this line will be tan with a stripe. Unfortunately, I forget the color stripe, and have no way to look it up.
There are 4 tan wires in this connector, one for each of the indictor lights. I will try to find the wire color.
BUT as I said at first, the tach is likely bad.

Also, there is no computer on that motor, and therefore no way to "read the codes" as you mention....

Edit: The best I can tell with limited literature to consult, is that the wire color will be tan with an orange stripe.
 
Last edited:

Terry Olson

Chief Petty Officer
Joined
Aug 20, 2005
Messages
415
The Check Engine alarm was used on the '98 V6 motors and indicated a fuel restriction. It was not used on smaller motors in 1998. You will need to check an owners manual for your motor to see if the alarm is even used on your motor.

The motor is a 2004 twin 50 and the owner's manual does refer to all of the various alarms mentioned in the original post except for the generic "check engine". I'm presuming that the issue isn't temp or oil, mainly because those alarm lights aren't lit and because it isn't running in SLOW mode.
 

Terry Olson

Chief Petty Officer
Joined
Aug 20, 2005
Messages
415
A steady alarm is an overheat condition. The steady stream from the tell tale means little. Verify you are not overheating by placing your hand on top of the head while running. You should be able to hold it there. The check engine light could be as simple as a faulty system check guage. All those used the guage but not all motors use the check engine circuit of that guage.

I strongly suggest running on 50:1 premix in your tank while you diagnose a bad guage, warning horn, or whatever is causing the alarm. Double oil will hurt nothing. It's actually recommended for certain situations.

The "water temp" light is not lit and the motor isn't running in SLOW mode. It does both when an overheat condition exists and I know this because I experienced this last summer when the intake screens were obstructed by weeds. I will check the head as you've suggested next time out to be sure, but I just don't think an overheat condition is the issue.

I thought about bypassing the VRO as so many others have but neither of the oil lights is lit and I have no reason to think this is the cause either.

Your mention of a faulty gauge has been my leading suspicion, but of course there's no way to test for this that I can think of. I don't know if this motor uses the check engine function or not, but I've run this boat for 3 or 4 years now and it's never been an issue. Ordinarily when I turn the key on it runs it's self-check --- the tone sounds briefly and each of the lights cycles on and off. Then they all go out and the buzzer silences. Now I see the same sequence but the check engine light stays lit and the buzzer changed to a different constant tone. It worked as usual for several hours during our last outing, and then the condition described began.
 

Terry Olson

Chief Petty Officer
Joined
Aug 20, 2005
Messages
415
No check engine function on that 50 hp engine. since the horn is controlled by the tach, it is very likely that the tach is bad.
Alternately, the tach has an 8 pin connector. If the line that would normally run back to the vacuum switch (on a V6)...if that line happens to be grounded, then the alarm will sound and the check engine light will light.
The wire color for this line will be tan with a stripe. Unfortunately, I forget the color stripe, and have no way to look it up.
There are 4 tan wires in this connector, one for each of the indictor lights. I will try to find the wire color.
BUT as I said at first, the tach is likely bad.

Also, there is no computer on that motor, and therefore no way to "read the codes" as you mention....

Edit: The best I can tell with limited literature to consult, is that the wire color will be tan with an orange stripe.

There is no tach on my setup, but I'll look for the leads and see if this leads me to any revelations.
 

daselbee

Commander
Joined
Jan 20, 2009
Messages
2,765
Well, no tach...then you have the systems check gauge. 4 lights in a 2" gauge. Same answer tho...bad systems check gauge.
 

Terry Olson

Chief Petty Officer
Joined
Aug 20, 2005
Messages
415
Well, no tach...then you have the systems check gauge. 4 lights in a 2" gauge. Same answer tho...bad systems check gauge.

That's my best guess - the most serious potential malfunctions have their own dedicated lights and the engine goes into SLOW mode when they're an issue. it runs like a champ, just like always. I just have no idea what the general "check engine" light refers to in my configuration. There isn't even the standard "take it to a dealer for service if this light comes on" in the owner's manual, whereas there is discussion about the other three lights on the gauge.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,137
If the new gauge doesn't fix it....The standard wire color for the "Check Engine" alarm is Tan/Orange. You might look for that wire in your engine harness and see if it has grounded itself, triggering the alarm.
 

Terry Olson

Chief Petty Officer
Joined
Aug 20, 2005
Messages
415
*** UPDATE --- SOLVED ***

The new system alarm solved the problem - thanks all for your time and advice.
 
Top