1992 Johnson 40HP Temp alarm trouble shooting

AK Ray

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This motor - J40TLENJ - has sat since 2004 and I have been slowly going through it the last week after buying it with a great old hull. After draining the oil out of the carbs (VRO system filled the lower carb over the years) I managed to get it started and it ran great. Runs great.

What happened was while learning about the VRO filling the float bowls with oil it was not starting and just running a few seconds on the gas the primer system squirted in. The engine never ran long enough to get water up from the pump (long shaft) into the block and eventually the block was hot enough to trigger the temp switch and sound the alarm.

I asked a local mechanic about what might be doing this, learned of the VRO oil filling the float bowl issue and prest-O change-O "She Lives!"

However, the high temp alarm would not shut off. It came on as soon as the key was turned. The engine is cool to the touch. The water pump is pushing water pretty good. But that darn alarm just keeps whining. One loud BEEEEEEEEEEEEEPPPPPPP. However, my ear tells me that there is a rhythm to this scream. I only notice it when I am trying to not listen to it. It kind of sounds like a really fast beep beep beep, but is lost in the scream of the BEEEEEEEEPPPPPP. I may just be hearing things.

So I turned to the iboats forums and found the dozens of excellent posts about how to test and what to test when there is an alarm. I did not know about the two oil alarms so that was handy. I had thought there was only one for the VRO system.

With the engine cold I turned the key and proceeded to unplug the temp switch. The alarm kept sounding its scream. The trouble shooting posts say that means it is a short or the buzzer is toast. I did the buzzer test and no more alarm. Sweet silence. However, the epoxy on the buzzer appears to be cracking so I will spend the big bucks and get a new one.

The basic trouble shooting left me with sorting through and testing the wire harness for shorts. I had to take the the top and side cowlings off to get to where I could see everything. I did find that there is a green ground wire on the trim/tilt harness that had melted and was pinched, but the wire was still good - just the cover was toast. This wire appears to run from the engine mount above the trim system to the engine block and does not actually appear to run current - just a ground.

What I found was really confusing at first. With the battery CONNECTED I determined which of the pins in the harness plug is the TAN wire for the temp alarm. The wire from the buzzer to the female harness plug is good with 0.2ohms or less. Then I tested the male harness pin to the temp switch bullet connector. WOW 2Mohms. that is a lot of ohms for what should be an open piece of wire about 8 inches long.

Now my head is hurting since this is supposed to be a wire that just feeds some voltage back to the buzzer telling it on or off. There should be a simple ohm reading from the harness pin to the temp switch connector showing it is an open circuit - just wire carrying the signal. Old Fluke meter is telling me it was reading 2Mohms when the battery was CONNECTED.

I pulled off the tape wrap and found a splice that has three wires going into one end and two from the other. Its about 2 inches into the harness behind the big red plug end with the male pins in it. See the photo.

J40tlenjtempswitchsplicev1.jpg


So here is how things tested out. A 0 reading means the fluke meter did not read anything - no movement on the screen, no reading search - just like when you do no touch the lead tips together (no continuity).

Battery CONNECTED
Ignition end of TAN wire to Temp switch connector (same side of splice)- 0.2ohms.
Ignition end of TAN wire to harness pin - 0.
Temp wire connector to harness pin - 2Mohms down (up?) to 0 as the air temp dropped.
VRO Tank connector to Temp wire connector - 2Mohms down (up?) to 0 as the air temp dropped.

Battery DISCONNECTED
Ignition end of TAN wire to Temp switch connector (same side of splice)- 0.2ohms.
Ignition end of TAN wire to harness pin - 0.
Temp wire connector to harness pin - 0.
VRO Tank connector to Temp wire connector - 0.

I went back and forth for a while testing with the battery connected and not. Sporadically getting the 2Mohms readings or a big 0. When things cooled down as the sun set there were no more 2Mohms readings. At first I was worried something was feeding voltage into something and I was getting something from that, but as it cooled off towards dark no more mysterious 2Mohm readings.

So it looks like the splice is shot. I can't tell if this is a factory splice build or a really well done repair. There was electrical tape on this end of the harness and the wraps were well thought out and even.

What confuses me is that if all the TAN wires for the sensor alarm system all come together in a single splice then how does that work when one of the sensors changes? I guess that is why there is "stuff" epoxied into the back of the buzzer. Those gyzmos can tell what is going on when a sensor changes.

Have I nailed the temp alarm scream down to the splice being rotten?

What is the best way to deal with repairing the splice?

Would jumping over the splice with some kind of home made test lead be a good way to test the alarm scream system? Trying to figure that one out is a head scratcher. How much of the system to I have to put back together, or just go from the temp switch all the way up to the buzzer with a single wire and bypass the whole harness?
 

Rick.

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

I feel your pain. I thought someone more knowledgable than I would have replied by now. If it weere me I would run a temp wire like you suggested and see it that stops the alarm. It should. Then you can replace the tan wire one section at a time until your problem is fixed. Sure does sound like it going to ground somewhere. Best of luck. I have a 95 - 40 Johnson but I have not worked on it very much(yet). Rick.
 

AK Ray

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Thanks Rick. When ever I make long detailed posts on internet forums I always wonder if I will get a response or not. It seems the best way to get people to chime in is to post vague questions that require people to ask for more details. Then provide a few bread crumbs with each post. It you appear to know what you are doing, nobody feels the need reply.

Right now I am waiting for the SELCO or Clymer service manual to be returned to the local library so that I can photo copy the pages specific to my motor. Waiting on some parts to arrive so I have time to wait on the library. Rivers are still blowing out ice so I won't be able to run the boat for two more weeks anyway.

However, what I am wondering about now is if this splice is actually a fusable link. It has a large lump in the middle of it that could be a fuse material. Or it could be just a well constructed standed copper wire splice with crimps at both ends and the middle.

I was hopping someone would chine in and say it looks funny for a splice. Once I can get my hands on the library copy of the service book I can see if the wiring diagram shows fusible links or not.
 

Rick.

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

My guess is a fusible link would cause a no power situation causing the motor not to run. If it were a fusible link and it was blown I believe it would open the circuit which would/should turn off the alarm so I don't think they would have put a link in the tan wire. It does look like a factory job compared to my work anyway. Not sure what clymer and seloc manuals will show. I would suggest searching on ebay for an omc service manual for your specific motor. If I get near my engine this weekend I will look at mine to see if I have the same splices. Where do you live that Ice is still breaking up on the rivers. Our lakes are mostly open now just over the last week or two. Rick.
 

AK Ray

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Thanks for the input on the fusible link possibility.

The service manuals that I have found so far are $80 from a manual distributor. I usually stay away from eBay due to my problems with PayPal from several years ago. They still owe me money.

I updated my profile. I am in Anchorage Alaska. Its been a long spring with cold sunny days slowing down break up. Just a couple more weeks though and the kings will be in and the rivers will be flowing.
 

Fed

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

G'day Ray, as far as I know there's a single tan wire that comes from the alarm back into the engine area and shorting this tan wire to earth will set the alarm off.
I think the different alarms continuous vs beep beep vs beep..........beep are caused by electronics built in to the VRO & Oil Bottle.

Continuous Beeeeeeeeeeeeep is temp switch shorting directly to earth with no electronics.
BeepBeepBeep (machine gun style) is VRO rapidly shorting tan to earth on & off.
Beep....Beep....Beep is the oil level bottle switching the tan to earth every 30 secs or so.

Disconnect the tan from the temp switch, the plug to the VRO and the plug to the oil bottle then turn on the ignition.

Edit: That join in the tan wires is simply that, just a join. (I think)
If the beeper is quiet the reconnect them one at a time to find out which one is giving the alarm.

If it still beeps when those things are disconnected then you probably have a short to earth in the tan wire or a faulty buzzer.
 
Last edited:

boobie

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Where those three tan wires come together is where a blocking diode is located and they keep false signals from putting the mtr into slow from false signals. Your two probs here might be a bad horn or else the oil tank electronics giving off false signals. Turn the key to on, disconnect the tan wire from it and if it keeps blowing you have a bad horn. If it stops, you have a tan wire grounded out some place. Then disconnect the wires coming coming from the oil tank and see what happens with the horn connected again.
 

AK Ray

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Fed and Boobie, thanks for your input. I should have checked back on here sooner. I scratched off the cover on that "splice" and found the diode. I didn't cut anything so I can seal it back up. I knew it looked funny for a splice, so I was gentle in my dissection wondering what it was. I have some high quality electrical splice coating "glue" that will do a good job.

What I have done is piece by piece connected the leads back into the harness. And what is a solid screaming alarm starts when the VRO leads to the tank are connected back to the harness. To me it is not very recognizable as a beepbeepbeep. About 5 seconds of really loud scream and then it starts what I would call "warbling". It is not what I would call a beepbeepbeep, but I can see why it confused me when reading the descriptions on here. Machine gun like beepbeepbeep is closer, but my horrible ear for sound thinks its a solid scream with no beeping at all. Makes me wonder what the high temp alarm will actually sound like.

Thank you everyone for your trouble shooting help. Now how am I going to get all those wires back under the cowling........I didn't know a remote controlled outboard had 20 feet of loose wire all coiled up under there.
 

AK Ray

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Re: VRO is very funny, but not in a Ha Ha way

Re: VRO is very funny, but not in a Ha Ha way

Plugging and unplugging getting the stuff back together. Thought I would test the VRO issue one more time. I unplugged the rubber connector between the harness and the VRO unit near the carbs. I tested the VRO leads from the tank again and.....no alarm. Huh?

Went back through all the testing procedures with the connections one by one and no alarms from anything. It was alarming from the VRO tank leads 30 minutes ago. After disconnecting the VRO mixer system and then plugging it back in and then the VRO tank leads all alarms have stopped.

Its like there is some kind of reset feed back loop built into the VRO mixer by the carbs.

So now on to returning all the harness parts back to their normal condition and replace the water pump.

Thanks everyone.
 

AK Ray

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Re: VRO is very funny, but not in a Ha Ha way

Re: VRO is very funny, but not in a Ha Ha way

Failure again. There is no magic reset button. Its just playing with me. I can see why people take out the VRO tank system. It is just mocking me now.
 

Fed

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Re: VRO is very funny, but not in a Ha Ha way

Re: VRO is very funny, but not in a Ha Ha way

I tested the VRO leads from the tank again and.....no alarm. Huh?
Did you remember to turn the key on?

It sounds like you're narrowing it down Ray, sorry to mislead you with the blocking diode & SLOW stuff my motor doesn't have that so it never entered my mind.
 

Rick.

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Well good for you and your mystery. Glad to hear you got her fixed and will be ready for the salmon. Rick.
 

AK Ray

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Its all back together tonight and running with the VRO tank leads not hooked up. After about 10 minutes it alarmed the low oil sound of a beep every 10 seconds or so. Hmm....low oil alarm with out the leads to the tank hooked up. I shut everything down and put away my tools to call it a night.
As I as picking up some stuff near the motor I heard a click like a spring had reset. Finished the tool pick up and then restarted the motor. It ran for an hour without making any more alarms. Tank leads still not hooked up since when they are they cause the warbling screaming beepbeep alarm. Which means that the VRO pump system is not working or is plugged.

But why would this alarm be coming from the tank leads and not the leads to the VRO pump? Those leads don't alarm. Is it because the VRO pump leads and the VRO tank leads TAN wires all join in the same spot on the harness?

What is weird about the sound of this alarm does not match up with what you find in this post by Joe Reeves. My alarm is coming from the VRO tank leads, but it sounds like the alarm I should be expecting from the VRO sensor up near the carbs. The alarm beeps are much closer than every other second which is why it sounds constant.

Makes me wonder which of all those oil lines is boogered up with the old gunk from sitting for 7 years.

It also was not smoking much as it ran tonight, but that might be because it no longer has pools of oil in the carbs.

Searching posts I did not see where not having the tank leads connected would be an issue. However, when folks bypass the VRO system they usually disconnect both sets of wires and then plug the oil port on the VRO doohickey so it does not suck air.

It was a long day in the spring sun, so time to say good night and sleep on it.
 

Fed

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

I'd start running premix @ 50:1 until you get it sorted, running double oil (premix +VRO) won't hurt it at all and it will keep your motor safe until the VRO oil usage is confirmed.
Running on premix will also allow you to test the no oil alarm to ensure it's working.

The Joe Reeves thread says it all.
Beeeeeeeeeeeeeeeeeeep Temp.
Beep/1sec/Beep/1sec/Beep/1sec VRO not pumping
Beep/30sec/Beep/30sec/Beep/30sec LOW oil in tank.
 

AK Ray

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

The Joe Reeves thread says it all.
Beeeeeeeeeeeeeeeeeeep Temp.
Beep/1sec/Beep/1sec/Beep/1sec VRO not pumping
Beep/30sec/Beep/30sec/Beep/30sec LOW oil in tank.

My alarm beep is about 5 seconds of solid beeeeeeeep then it starts into
Beep/0.01sec/beep/0.01sec/beep when the VRO tank leads are connected back into the harness.

A 1 second pause between beeps would be pretty noticeable, but my beeps are so close together than they form a warble and not a series of beeps. Which is why I thought it was the high temp alarm.

When just the high temp sensor lead is connected there is no alarm so that system is working. When just the VRO pump is connected there is no alarm. However, maybe this alarm only works when the engine is running and oil is being pulled into the pump. Unless the sensor is toast I can't think of a reason it would alarm without something to measure when the pump is working.
Why I get a nearly constant alarm from the low oil leads from the tank, don't know. Maybe both VRO electrical systems have to be connected to function.

Considering how long this system has spent sitting it would not surprise me if the whole VRO pump system is clogged with oil goo. Without a manual all I can do is take the hoses off and clean them out. Since it is not raining and appears to be another nice spring day I think I will dig back into the engine and clean as much as I can get to.

After reading up on the VRO system it appears that without proper maintenance they "fail". Use of the canned engine cleaner and the little inlet port on the fuel primer is supposed to be the best way to keep the fuel system maintained and functioning.
 

Fed

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

I think you have a faulty level sensor or a grounded wire to the oil tank & your beeper is also getting a bit scratchy.

If I were you I'd confirm the oil usage running on premix & also test the VRO alarm.
If that is all OK then I'd fix the tank level sensor and/or wiring.
If the VRO also has a problem then it may be worth considering premix due to costs.
 

Rick.

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Re: 1992 Johnson 40HP Temp alarm trouble shooting

Excellent idea about running the premix from Fed. That is good insurance until you determine the root cause of the beeps. Thought we were through with this yesterday. Rick.
 
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