1999 Johnson 70 hp plee 2 stroke alarm wiring question

[24 Albemarle]

I recently bought this motor and it runs well, VRO is removed and were on the mix. I have original control box with a horn mounted under the dash, when igntion switch to on position all warning lights light up and then go off one at a time as well as a momentary beep. I think this is as it should be, normal. Howerver when I ground out the wires from thermostat, I am not getting horn. I have original manual but only refers to accessory manual for remotes and their functioality, which manual I don't have (70$). The wiring diagram shows tan wires (with various traces) to be alarm functions. at control end of wiring harness these tan with trace colors seem to not be there, so I assume they are going into the shift control box.? As stated the VRO system is removed and I had disconnected the plug on engine block ( to avoid horn actuation relative to VRO malfunction) I have reconnected this plug to see if I can get an alarm horn from VRO but to no avail. Again engine runs fine no heat issue, new thermostat, water pump etc. runs at a nice warm temp as per thermostat dictates. I know this is a simple wiring issue and I suppose I need to get a look at a wiring diagram for what happens at the control box end to be able to sort it out. As stated this is a new to me motor and I don't really have the benefit of history with this motor to know how it should function. I have read all sorts of posts with horns that go off but not one that won't go off, especialy when prompted by grounding out tan with blue trace (temp sender). Any ideas or suggestions would be appreciated.

 

[daselbee]

Try shorting tan to ground WHEN ENGINE IS RUNNING.
Post back results.

 

[24 Albemarle]

Thanks, I'll try that. I worked on it a little while today and checked with a continuity test the #6 wire to tach from engine harness and wire was good. then tracking tan wires (alarm ) from plug on rear of motor(#6) to wire junction for vro and thermostat junction, I found lack of continuity across this area, so I finally cut (carefully) the electric tape and discovered the two tan alarm wires merge into one clear tube connector changing to one solid strand wire with what appears to be a diode (pure speculation) in the middle, that comes to the #6 terminal on the afore mention plug on rear of engine. Carefully splitting the tube open, I can't get continuity across the wire with this black diode like thing in the middle. (I have a feeling I'm going to hear an omg you didn't do that! ) I don't know what it is , it has a #6 written on it.
My horn or beeper has two wires that come from the tach it beeps once when ignition is turned on. I hope what you suggested is all that is needed as I want my beeper to work for at least the hot alarm. I like to understand how things work and everywhere I have read the same " just ground the tan thermo wire with the key on and the alarm will sound.) No one has written with the engine running so maybe I have made a mountain out of a mole hill. (not the first time) Does anyone know what this mystery black thing is and does? More importantly did I screw up opening the tube. I can seal it back easily with a hot melt glue then wrap etc. Thanks

 

[daselbee]

Do you misunderstand? The horn only works in it's alarm function when engine is running. The horn signal is triggered by the tach or the horn driver module...depends what you have.
That is the way it works on Systems Check engines.

You did a whole lot of work and destruction of the harness for nothing, in my opinion.

 

[daselbee]

everywhere I have read the same " just ground the tan thermo wire with the key on and the alarm will sound.) No one has written with the engine running

Grounding the tan wires with key ON, and listen for horn is the accepted method for pre 1996 old design warning systems.

 

[24 Albemarle]

Thanks, "Try" shorting tan to ground with engine running" didn't sound as definitive as your second post but nothing was destroyed and is better now than before as I was able to clean up some of the wires Johnson boys didn't know what to do with. I am still wanting to know how the system will sound the alarm if it sounds and you turn off the key, assuming the engine to be in alarm mode when you turn the key back on will the hot alarm sound or do you have to start the engine again for the alarm to sound? I now know that the alarm wire has a diode in the line and I am supposing it keeps the voltage from a possible back feed to the power pack? i would have just ran it and tried but I had already drained fuel system down for the winter before I tackled this issue (never thinking I would need to run the motor to work this out). Not an excuse, just how it worked out this time. Thanks for you time.

 

[daselbee]

Sorry...I should have been more assertive in my first response. I never figured you would go for the hardest fix first (wiring harness disassembly and inspection). Figured it would be a simple thing to just start it up and try my suggestion. Then if it still was not working....go for the gusto....

Anyway, here is the deal.....the tach or the horn driver (depends which you have), is a "smart device" in that it takes multiple inputs from tan wires in the harness, determines which one is active, ie. shorted to ground due to a fault, and turns the horn on, and lights up the appropriate light.
For example, when running, and if the plain tan wire goes to ground due to overheat, the horn sounds FOR TEN SECONDS and goes off.
The horn is driven by the tan/blue wire in that same Deutsch connector plug. If I remember right, there are about 8 wires in that plug, purple, black, grey, and five more various versions of tan.
The tach requires the signal input on the grey wire (tach signal from engine) to detect that the engine is running before it can do this fault detection.
You as operator are supposed to look at the lights, and determine which fault to correct.

I suspect, but do not know absolutely, that if a fault exists (hot for example) that when you key ON, and the Systems Check "checking" sequence occurs, the horn will sound. I suspect it will. But I know absolutely for sure that if you key ON, fiddle around a bit and then finally get to shorting the wire to be tested to ground, in other words after the initial sequence has completed, the horn will not sound. That is a fact.

Examine the wire colors in the plug that plugs into the back of the tach. They are for the most part tans with various stripes. They come from the engine fault monitoring areas.....in your case....no oil, low oil, and overheat. There is a fourth monitoring point on V6s...and that is a vacuum switch in the incoming fuel line to detect a restriction if one exists from the tank to the fuel pump.

 

[24 Albemarle]

Wow, that was awesome! I now have the picture and am absolutely grateful as I understand. Why manual writers couldn't put a paragraph like that in a manual and help those of us that have not worked on 20,000 motors to grasp the functionality of their design.( and maybe some that have) Thanks, I have a lot of experience with a lot of different motors and mechanical objects and have grown up having to do for myself, not a complaint by any means as it has been a driving force to learn. Thanks again for your assistance.