Johnson 150 1996

[Damifudo]

I have the check engine system in the tach. I had to add a loud buzzer to the system for the alarm. Now I notice that the buzzer has a low noise comming from it at times when I have the Key on. The alarm works if there is a problem it just seems to leak some voltage thru to make the alarm sound like a quiet duck when key is on. I had no idea for a while where the sound was comming from untill I crawled up under the dash and found the alarm making a low constant sound. Any ideas its pretty anoying when your idling around.

 

[tashasdaddy]

Re: Johnson 150 1996

wiring problem to horn. it should not make a sound until the sensor is grounded.

 

[jonesg]

Re: Johnson 150 1996

Try disconnecting sensors one by one, if you can't isolate it under the hood its probably under the dash.

Disconnect the signal wire (grey?) from the horn,
if it keeps buzzing its dead (or a dud).

 

[Damifudo]

Re: Johnson 150 1996

If I disconnect the gray wire to the horn its quiet. the horn only has two wires the signal and the ground. Its like it is pleading through from the tack just a small amount to make it make an annoying noise. When I ground the over heat sensor it screams nice and loud and lights the light on the tach for hot. If I raise the oil sensor it screams loud and says low oil like it should. When it makes the noise no lights are lit on the tack, Not sure how it can be miss wirred since it only has two wires going to it. Its a a piezo buzzer from radio shack not the orig one that came with the motor.

 

[Damifudo]

Re: Johnson 150 1996

This is still a issue. I have even tried to install a choke in the line. Then it will not work at all. I about to assume I have bad tach as that is the only thing I know that would allow a voltage through to the buzzer when there is no alarm. This thing sound like a wounded duck at low speed. Again the unit sounds very loud if there is a issue and the lights on the tach come on.

 

[clanton]

Re: Johnson 150 1996

Horn should not have gray wire. Wire from tach to horn should be tan. Does system self test, one beep when key turned on? Disconnect the sensors, then test, 1 oil tank sensor, 1 VRO pump sensor, 1 fuel restriction sensor, 2 over heat sensors, still buzzing change tach.I will verify wire color from manual tomorrow.

 

[will62]

Re: Johnson 150 1996

Try adding a low ohm resistor (~4.7) in parallel to the buzzer. Even before you reach the warning threshold, you could have a few milliamps of current in the circuit. Some of those Radio Shack piezo buzzers will kick at about 5 milliamps. The current may be too low for your warning lights to come on, but high enough to cause the piezo to hum.

 

[SparkieBoat]

Re: Johnson 150 1996

sounds like your temp sensor may be bleeding through some..you should ohm test both temp sensors, if one is way higher than other there is your problem..also could try unplugging temp sensors one at the time. you can also ohm test the ground wire going to buzzer.

 

[clanton]

Re: Johnson 150 1996

Alarm horn wires are 1 purple, 1 tan/blue stripe.

 

[jere1972]

Re: Johnson 150 1996

try placing a 400-1000 microfarad capacitor across your wires at the horn, radio shack has them pay attention to the voltage rating use 30v and above, the capacitor will filter out any a/c ripple back to ground, leaving a clean dc source voltage to the horn, you can also place diodes in series with your horn one on the neg side one on the pos side diodes are polarerized banded(cathode) is neg side, non-banded(anode) is positive, the diodes with only allow current/voltage to flow in one directon, but really seems like you have an induction humm on your wires, the capacitor should filter that out!

 

[daselbee]

Re: Johnson 150 1996

Clanton has it right...you got the horn wired wrong. Wire it right.

 

[Damifudo]

Re: Johnson 150 1996

The horn cant be wired wrong there is only two wires and it works properly when there is an alarm. I will give the capacitor a try. I did try a diode that didnt work. The boat is not at my house right now its in winter storage but as soon as I get a chance I will go give this a try. I dont have a battery in the boat at this point. I dont think it is wired wrong there are two wires going to it from the systems check from the tack. When any of the lights come on the buzzer screams nice and loud as it should.

 

[clanton]

Re: Johnson 150 1996

If the wires to the horn is correct, and sensors wires not shorted. The tach is bad, tach has logic which work the lights and the self test.

 

[daselbee]

Re: Johnson 150 1996

The Systems Check tach has an 8 pin modular plug mainly containing a bunch of tan wires with stripes. The tan/blue wire is the wire that drives the horn. If you have a gray wire driving the horn, you are driving it with the tach signal. Because gray is the tach signal.

I still think you have it wired wrong. If I am not mistaken, there are purple, gray, and black pigtails for use in wiring tachs without the Systems Check feature. Those should be capped off, and the 8 pin plug should be used, in your case.

EDIT:

OR, you have posted the wrong colors above, thereby misleading us.

 

[will62]

Re: Johnson 150 1996

I don't think that it's a wiring problem, when he grounds the temperature switch, the horn and lights activate. Another forum member brought up the color grey (post #3), and Damifudo rolled with it. May have been a while since he wired it, and didn't remember the colors. I still think that the problem is related to the Radio Shack piezo buzzer. As I mentioned in my previous post, most of those buzzers operate in the low milliamp current range. They are not balanced to the rest of the circuitry in the warning system.

When the key is on, the horn always has 12v (hot), the temp switch supplies the ground. The temp switch is not an on/off switch. It starts with a resistance too high to allow the flow of 12v current, but the resistance steadily drops as the temperature increases. Here are some numbers that I took when I was testing my temp switch:

Temperature (F) - resistance
65 - 1.5 megohms
160 - 1.1 kilohms
205 - 0.1 ohms
(Note that the circuit is never actually "open")

Some warning horns designed for boats, require 500 milliamps to operate. If your current is below that, you won't hear a peep. The resistance on the switch would have to drop to 24 ohms to reach that threshold current. I think that Damifudo's problem is that he has installed a piezo buzzer that operates in the low milliamp range. When the temp switch reaches the 145-160 range, the resistance drops enough to allow the flow of 8-10 milliamps. I'd almost be willing to bet that if he checked the specs for the buzzer, the operating current would be slightly higher than that. The humming that he is hearing, is that buzzer approaching operating current.

 

[daselbee]

Re: Johnson 150 1996

^^^^^^^^^
Disagree.

The systems check tach controls ALL the horn function. The inputs to the tach are the tan signal wires. The tach detects a grounded tan lead (hot for example) and lights the appropriate light. It also turns on (drives) the horn. The horn current flows from the purple wire at the horn, thru the horn and to ground INSIDE the tach. The ground provided is switched inside the tach.

This is a different system from the old warning system that you have described.

If he is driving his horn with a grey wire, he is driving it with his tach signal.

If he is driving it with the tan/blue, then his tach is bad, allowing leakage on the tan/blue thru the tach to ground.

EDIT:

One other thing about the Systems Check tach/alarm system. The alarm WILL NOT SOUND unless the engine is running. If you want to test the alarms, and turn the key to ON, and then systematically take the sensor wires to ground, the lights on the tach will light up as expected, but the horn will not sound.

Start the motor and do the same test, and the lights will work as well as the horn will sound.

Also, the horn will only sound for about 10 secs. Then it goes silent, even though the warning fault is still present. They are depending on the operator to hear the horn and check the tach lights for the fault.

 

[clanton]

Re: Johnson 150 1996

Radio shack should work fine.