Continuous Alarm from OMC Control Box

[seabreeze101]

Hello,
I have a 1991 Johnson 100HP 2-stroke engine with OMC control box. The alarm in the control box audibles continuously upon turning the key -- even without starting the engine. The alarm normally beeps once when I turn the key prior to starting the engine.
I have read older threads (from 2003) in this forum that if I open the control box and disconnect the tan wire on the alarm, it would be an indicator of a faulty alarm or not. That is, if I turn the key and the alarm stays on with the tan wire off, then the alarm is bad. However, if the alarm goes off after I remove the tan wire, then it is indicative of something else (oil sensor, overheating, etc.). In my case, after I removed the tan wire, the alarm does turn off. However, I'm not so certain about the diagnostics in my situation -- I'm not even starting the engine. Would it still be a defective alarm issue? These alarms are hard to find but I did locate a used one on eBay for $50 but am hesitant to buy it if it's more than a faulty alarm. Any assistance is appreciated.

 

[Joe Reeves]

From what I've read..... The engine IS NOT running, and turning the key ON causes the warning horn to sound steady and constant. Removing the TAN wire from the horn, the horn shuts OFF. Okay... you have either a grounded TAN wire at some area OR a failed sensor. Reconnect that TAN wire to the horn and with the horn sounding off, start disconnecting the same TAN wire from the engine's sensors.

When you disconnect that TAN wire from a specific sensor and the horn shuts down, you've found the offending sensor.

On your model (1991 100hp), there would NOT be VRO or a related oil tank.

That leaves just the two overheat sensors at the individual cylinder heads. Simply disconnect the TAN wire from the overheat sensors at the top area of the cylinder heads.

If with both overheat sensors disconnected, the horn still sounds... that TAN wire is grounded somewhere.
.

 

[seabreeze101]

Joe, thanks for your reply. I will try your suggestion later tonight and follow-up!

 

[seabreeze101]

Joe Reeves,

Just for clarification, I do have an oil tank underneath the console and the guy who sold me the boat said that it injects oil into the fuel. I've also uploaded two pics to provide some reference. I found two different "tan" wire leads coming into the engine. The red circled lead is paired with a black wire and it eventually feeds both sensors (the port side sensor is shown and circled in red as well). The blue circled lead connects to the bolt towards the back of the block and ties back to the temperature gauge? (I'm guessing) -- which by the way, the temp. gauge didn't move a budge when I took the boat out last week for a continuous 30 min ride at roughly 3,000 rpm. There was no alarm, and the water temperature was cold but the reading did get me a little worried.

I did the following:

1. Reconnected tan wire to alarm in control box.
2. With alarm sounding, I disconnected each sensor's plug one at a time (the sensor is circled red next to blue circle).
3. The alarm did not shut off with each sensor disconnected.
4. I then disconnected both sensors - still no alarm shut off.
5. Reconnected both sensors.
6. Disconnected the red circled tan lead that is paired with the black wire. The alarm shuts off.

I am not sure what to make of this. Could both sensors be bad or would it still be an issue with the tan wire "grounded somewhere" as you mentioned and how can I solve this? I also read somewhere that one guy ignored suggestions about running through the motions as people suggested, but simply just replaced the alarm and it worked for him (he was assuming his engine wasn't overheating and sensors were good).

 

[Joe Reeves]

I looked at those pictures but couldn't make out what I was looking at... no idea what those wires are.

The 1991 100hp Evinrude/Johnson DOES NOT incorporate a VRO pump which automatically mixes various ratios of oil with the gasoline before being delivered to the carburetors... it has a small straight fuel pump instead. What is the model number of that engine?

Seeing as how you DO HAVE a oil tank, then it stands to reason that you also have a VRO pump so you have two more sensors to check as follows.

With the horn sounding:
VRO sensor = Follow the wires from the VRO to its connector and unplug it to disconnect the sensor.

Oil tank sensor = Trace the dual wire cord from the oil tank to the engine. One lead is an obvious ground. The other lead is connected to a TAN wire.. disconnect this wire to disconnect the sensor.

Did disconnecting one of these cause the horn to stop sounding?

Get than model number to us. Your engine is either not a 1991 100hp OR someone has been doing some modifying to it.

 

[seabreeze101]

The model number is VJ100SLEIE.

 

[boobie]

If you disconnected the tan and black wires and the horn shut off and the wires come from the oil tank, that's where your problem is. The sender in the oil tank which did give trouble.

 

[seabreeze101]

Thanks boobie - my response to you ties in to my reply to Joe Reaves. Joe - my apologies - now that I've seen the original pictures that I uploaded, they are just awfully small. They were intended to show up much larger. So, I have included Dropbox links to those two photos below. Hopefully they show up in full display for you. If not, then I will just say for now that there was a TAN/Black wire pair with a round black cover/housing holding them together by a metal clip. I disconnected just the TAN wire and the horn stopped. I traced them forward and it appeared that the TAN wire eventually led to the port side temp sensor (but did not verify by doing a continuity check with a multi-meter). So, I'll re-check if this pair comes from the oil tank or really leads to the temp sensors. I'll also check the VRO sensor.

Picture 1: TAN/Black wire pair atop the red housing. Traveling forward, there's two disconnection points for the TAN/black wires next to the red housing. Red circles indicate the same TAN/Black wire pair. The blue circle indicates a single TAN wire that what I'm thinking comes from the temperature gauge (see Picture 2 for where it connects to).

Picture 2: TAN wire disconnected (large red circle). Alarm shuts off. This TAN wire eventually leads to the port side temperature sensor circled red (alarm does not shut off when disconnected).

 

[Joe Reeves]

The engine is indeed a 1991 100 hp Johnson... VJ100SLEIE

Beware!..... Trying to check the origin of those wires with a ohm meter will drive you nuts as "all" of those connections eventually become "one wire" that leads to the horn, which in turn results in a false reading.

You've already disconnected both overheat sensors at the cylinder heads and the horn continued to sound. This proves that the problem is not with either of those sensors.

If you disconnected the wire that leads to the oil tank and the horn stopped sounding... you have a faulty sensor within the oil tank!

 

[seabreeze101]

Joe - Your last response confirmed what has been the issue all along about a faulty oil tank sensor. I decided to take drastic measures by cutting the TAN wire coming from the oil pick-up assembly (Picture 3) to make certain that this wire (and the black one) goes to bullet type connectors shown in Picture 2 of the last post. Leaving the TAN/black bullet connections from the engine intact, turning the ignition key did shut off the alarm. I don't mind soldering wires back together as long as I have some peace of mind that there's no wild goose chase (for example, with simply a faulty alarm in the control box or grounding issue). Now I'll be looking for a pick-up assembly, which doesn't come cheap with new stock 5008618 replacing old stock 0176636 - I assume old stock is still fine to use. Hopefully I can find the older stock on eBay at significantly lower cost. Now I have a temperature gauge issue that I've got to post on a new thread! Thanks for your help!

 

[seabreeze101]

Joe - Your last response confirmed what has been the issue all along about a faulty oil tank sensor. I decided to take drastic measures by cutting the TAN wire coming from the oil pick-up assembly (Picture 3) to make certain that this wire (and the black one) goes to bullet type connectors shown in Picture 2 of the last post. Leaving the TAN/black bullet connections from the engine intact, turning the ignition key did shut off the alarm. I don't mind soldering wires back together as long as I have some peace of mind that there's no wild goose chase (for example, with simply a faulty alarm in the control box or grounding issue). Now I'll be looking for a pick-up assembly, which doesn't come cheap with new stock 5008618 replacing old stock 0176636 - I assume old stock is still fine to use. Hopefully I can find the older stock on eBay at significantly lower cost. Now I have a temperature gauge issue that I've got to post on a new thread! Thanks for your help!

Picture 3: Cut TAN wire from pick-up assembly; alarm stops.

 

[boobie]

The new oil tanks don't have the electronics in them like the old ones did. Too much trouble with the old ones. All the new ones have is an on / off switch so all you'll get is a steady horn for low oil.

 

[seabreeze101]

Thanks for the insight boobie.

 

[Joe Reeves]

The new oil tanks don't have the electronics in them like the old ones did. Too much trouble with the old ones. All the new ones have is an on / off switch so all you'll get is a steady horn for low oil.

Boobie.... You'll recall that I retired back in 1991 which brings up the question...... So now, a Overheat, Fuel Restriction, and Low Oil encounter "ALL" result in a constant steady sounding of the warning horn, and one has to take a guess of the three?

 

[boobie]

Joe, this all came out with System Check in 1996 where you have a gauge with lights in it to tell you what to look for. And if you didn't have a gauge you'd have to guess except no oil from the VRO.

 

[boobie]

Yes, just keep an eye on the oil level.

 

[Robinsom]

on the 1989 140 Johnson I have only one tan bullet type connector on port side of motor - disconnected and faint alarm stayed on. I already tried temp sensor port and stbd connectors at cylinder heads and alarm stayed on. I thought picture 2 bullet type tan connector was part of oil tank circuit and if that was problem it would have cut off alarm when disconnected at bullet type connector . Should I pull back black heavy sheathing of oil tank wire and cut tan wire - will I be able to splice that back together if not problem.

btw - did continuity check on cylinder head temp sensors and was getting around 2Mohms - but think tan connector goes through electronics of power pack - not sure if should read close to "0" ohms or not. Also ground each cylinder head tan wire to cylinder head and stbd increased alarm sound pitch and port did nothing. still think it is low level alarm issue in oil tank as I replaced steering cable and tank was on its side for extended period of time, but don't want to cut if not pointing.

btw - at horn - 12v on purple wire and 8.6v on tan wire when on or off?

Suggestions??

 

[Robinsom]

on the 1989 140 Johnson I have only one tan bullet type connector on port side of motor - disconnected and faint alarm stayed on. I already tried temp sensor port and stbd connectors at cylinder heads and alarm stayed on. I thought picture 2 bullet type tan connector was part of oil tank circuit and if that was problem it would have cut off alarm when disconnected at bullet type connector . Should I pull back black heavy sheathing of oil tank wire and cut tan wire - will I be able to splice that back together if not problem.

btw - did continuity check on cylinder head temp sensors and was getting around 2Mohms - but think tan connector goes through electronics of power pack - not sure if should read close to "0" ohms or not. Also ground each cylinder head tan wire to cylinder head and stbd increased alarm sound pitch and port did nothing. still think it is low level alarm issue in oil tank as I replaced steering cable and tank was on its side for extended period of time, but don't want to cut if not pointing.

btw - at horn - 12v on purple wire and 8.6v on tan wire when on or off?

Suggestions??