70hp Johnson warning horns??

[Bass Runner]

Can anyone tell me if the 1974 Johnson 70hp motor have warning horns? If so where are they located, i have seen what looks like sensors on the motor but cant find the horn anywere, where are they located in the control? on the wiring digram on the motor it list sensors but can't find a horn anywhere.

 

[ob]

Re: 70hp Johnson warning horns??

The warning horn is in the control box if your rig has the original omc controls.That 70 hp engine should have just one overheat sensor located on one side of the head cover.If there is another sender installed on the other side ,it is likely for a temp guage.If you have the old style omc side mount controller,some of them had a test slot for the horn.On ones so equipped ,by lifting the fast idle lever ,it exposes the slotted opening.With the key in the 'on' position, a key or similar metal object is inserted into the slot completing the alarm circuit and the alarm should sound.In any case your horn should be within the throttle control box.

 

[Bass Runner]

Re: 70hp Johnson warning horns??

Could have fooled me, I didn't have a clue, is the horn supposed to sound momentarily when you turn the key on like the newer motors or just the test slot to test the circuit?

 

[ob]

Re: 70hp Johnson warning horns??

The older OMCs did not have the system check beep when turning the key on.Your 74' model may or may not have the test keyslot under the fast idle lever.

 

[Bass Runner]

Re: 70hp Johnson warning horns??

I went and looked and it didn't have the slot is there any other way to test the horn? Tomorrow i am going to tear the control apart and see if I can find it, what does it look like just a round speaker or what?

 

[rickdb1boat]

Re: 70hp Johnson warning horns??

Look for the tan temp. sensor wire on the back of the head near the top spark plug, which is connected to the temp. sensor. Remove the wire from the sensor and with the key in the ON position, ground it to the engine block. It should sound at the control if it's working or even their. If you take the control apart, you will not miss the horn. About a quarter in size...

 

[Bass Runner]

Re: 70hp Johnson warning horns??

Originally posted by rickdb1boat:<br /> Look for the tan temp. sensor wire on the back of the head near the top spark plug, which is connected to the temp. sensor. Remove the wire from the sensor and with the key in the ON position, ground it to the engine block. It should sound at the control if it's working or even their. If you take the control apart, you will not miss the horn. About a quarter in size...

I think I remember a round green colored thing in the lower back side of the control but didn't ever pay attention to it, I will try the unhooking it and ground test to see if it works, with the through the prop exhaust it is hard to tell if there is water coming out there or not but it dosnt seem to be overheating. It's a real good old motor and hate to ruin it, I have a 86 70hp and it just dosn't have the power that the 74 model has.

 

[Bass Runner]

Re: 70hp Johnson warning horns??

well tried the test and nothing happened? unplugged the wire going to the sensor and shorted it to ground like you said and nothing, where do i go from here?

 

[ob]

Re: 70hp Johnson warning horns??

Don't usually unplug the wire but as long as you grounded the side that is (not) on the temp sensor side with the key 'on' then it should have sounded and horn in controls is likely defective or wiring to it is not making.<br /><br />Post back with which side of the disconnected wire you grounded.If you grounded just the loose end hanging from the sensor ,nothing will happen.

 

[rickdb1boat]

Re: 70hp Johnson warning horns??

OB is right. I should have specified that you want to ground out the wire going to the control. Thanks OB....

 

[Bass Runner]

Re: 70hp Johnson warning horns??

Ok I went back out and checked it out, there is only one plug and the other wire is hard wired into the buss bar at the rear of the motor, cant tell for sure where the other wire goes, it look like it goes into the block of the motor, do i need to take the cover off the buss bar and ground from there?

 

[ob]

Re: 70hp Johnson warning horns??

The one that looks like it goes into the block is the end that leads to the temp sensor.If you unplugged this wire ,ground the other end that doesn't look like it goes in the block.Make sure the key is in the 'on' position.If alarm doesn't sound ,you have a faulty horn or wiring.

 

[Bass Runner]

Re: 70hp Johnson warning horns??

The wire going to the block has no plugin, just the one going to the bus bar, with the key on is the connection at the plugin supposed to be hot or is it a ground sys?