Johnson 30 overheat warning horn. 96 Engine.

[glennkil]

Confused with this one as wiring diagrams on the web show the tan wire providing earth from the sender back to one side of the horn and the purple wire providing a positive through the ignition switch. Errr, it isn't so and the tan wire goes into what I think is the powerpack?? I think this provides a signal for limp home mode when engine get hot. Turning the ignition key on and grounding the tan wire doesn't result in the horn going off. Should it? I'm guessing the horn is in the control unit? Will there be springin', poppin' of things that are hard to put back together if i remove the cover to access it?

 

[Joe Reeves]

Keeping it simple....... 12v is always constant at the "B" (battery) terminal of the ignition switch.

When key is in the "ON" position, 12v from the "B" terminal is connected to the "A" (accessory) terminal of the switch.

A purple wire leads from the "A" terminal to the slide on terminal of the horn furthest away from its black ground wire, providing 12v to the horn.

A tan wire leads from the remaining slide on terminal of the horn to the "heat sensor" in the cylinder head.

If the engine overheats, the heat sensor shorts out to ground, completing the circuit and the horn sounds off.

Now..... With the key in the ON position, grounding the tan wire of the heat sensor to any powerhead ground, the horn should sound. If it does not, a problem exists. Get back to us with what you find.

 

[glennkil]

Keeping it simple....... 12v is always constant at the "B" (battery) terminal of the ignition switch.

When key is in the "ON" position, 12v from the "B" terminal is connected to the "A" (accessory) terminal of the switch.

A purple wire leads from the "A" terminal to the slide on terminal of the horn furthest away from its black ground wire, providing 12v to the horn.

A tan wire leads from the remaining slide on terminal of the horn to the "heat sensor" in the cylinder head.

If the engine overheats, the heat sensor shorts out to ground, completing the circuit and the horn sounds off.

Now..... With the key in the ON position, grounding the tan wire of the heat sensor to any powerhead ground, the horn should sound. If it does not, a problem exists. Get back to us with what you find.

That's the problem Joe the tan wire from the sensor doesn't go to to the horn. it goes to the power pack and yes if i ground it out with the key turned i don't get the horn. Don't these engines have "limp" mode where revs are limited if the engine gets hot? This would explain the sensor wire going to the power pack.

 

[Joe Reeves]

Limp mode??..... I think you're speaking of the S.L.O.W. feature. If that exists on your engine, the heat sensor would have two wires leading out of it.How many wires are at the heat sensor? What color is the wire(s)?

Check the wire further. Is it still TAN at the horn or has the color changed? (retired in 1991)

If more than one sensor exists at the engine, the color from the horn to the sensors would remain the same color and lead to "All" sensors... "However"... the signal to the horn would be activated only by the problem involved ie... overheating (steady beep), no oil at VRO (beep every other second), low level at oil tank (beep every 40 seconds or so), etc keeping any conflict non existent.

Do this..... With the key in the ON position, there should be 12v applied to the same color wire leading from the horn at the heat sensor. Is 12v present there?... If so, and the horn isn't sounding, either the horn has failed (check it direct at a battery) or a electrical problem exists.

 

[glennkil]

I'm confused too but a tan wire goes from the power pack to a bullet connector and a short piece of tan wire that runs to the near the top of the head to another bullet connector and the temp sensor from the head plugs into this. From what i read a "SLOW" mode on 96 30's isn't right. Power pack is a CD2SL/6100. Engine is a HJ30ELEDB. I did find this though!

Engines with S.L.O.W. Features: If the customer is complaining that the engine won’t rev up and shakes real bad, the S.L.O.W. function could be activating. If the engine is NOT overheating, a temperature sensor or VRO sensor failing early can cause this problem. Disconnect the TAN wires at the power pack and retest. If the engine performs normally, reconnect the tan wires one at a time until the problem recurs, then replace the last sensor you connected. Make sure that all of the TAN wires are located as far as possible from the spark plug wires. Also check the blocking diode in the engine harness

 

[glennkil]

Limp mode??..... I think you're speaking of the S.L.O.W. feature. If that exists on your engine, the heat sensor would have two wires leading out of it.How many wires are at the heat sensor? What color is the wire(s)?

Check the wire further. Is it still TAN at the horn or has the color changed? (retired in 1991)

If more than one sensor exists at the engine, the color from the horn to the sensors would remain the same color and lead to "All" sensors... "However"... the signal to the horn would be activated only by the problem involved ie... overheating (steady beep), no oil at VRO (beep every other second), low level at oil tank (beep every 40 seconds or so), etc keeping any conflict non existent.

Do this..... With the key in the ON position, there should be 12v applied to the same color wire leading from the horn at the heat sensor. Is 12v present there?... If so, and the horn isn't sounding, either the horn has failed (check it direct at a battery) or a electrical problem exists.

One tan wire from the overheat sensor and it connects to the power pack. Its not to say that someone else changed the head previously and it came with a sensor that had only one. I will check the horn itself tomorrow by applying ground directly to one side of it. Where is it??? Inside the forward control box? I's not a VRO engine.