Warning Horn

[FRED-E]

I am working on N12M 1975 T337. The problem is intermitten. When the gear is retracted the horn goes on & no it is not a squat switch. It may be the dual warning unit (2070005-15). Does anyone have this unit for sale ?
Thanks
Fred N358

Fred,

I had the same problem, except mine only occurred in high moisture conditions, e.g., clouds, rain, etc. It was the wiring connection at the micro switch on the cam. At least worth a look if you haven't already.

Keven
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Wage Insurance Forum

[Pete Somers]

Fred
I have never known a dual warning unit give any trouble, it is always wiring. as i explained earlier. A intermittant short circuit on the throttle micro switch wires or moisture on the micro switches will set the horn off.
Need to start disconnecting wires to fiind this one??

Regards
Peter

[FRED-E]

Pete
Both throttle micro swt's were taken out of the system & we still had the problem.
I have another question, when the horn goes off it is not a worbel sound & the manual said it should be & it is not the sound of the stall warning which is a different sound.
One other stange thing, with the squat swt disconnected, master on, throttles forward, pump CB pulled, my partner shorted the squat swt control wires together, sometimes the horn would go on & sometimes to go off & sometimes the Avionocs Master would come on !!!!!
Strange things are happening !!!!!!!!!!
Fred N358

[Pete Somers]

Very strange??

Fred, a couple of questions.

On the '75 337G the stall and gear horn are wired up to the speaker, does the horn come thru the speaker?

It is a differant niose to the intermittant 'squeak' you get on the horn type (on older models).

Did you take out the throttle micro switches at dual warning unit??

As you operate the squat switch can you hear a relay operate in the center console?
If this relay does not energise when the squat switch is operated the horn will sound. So it does sound like this relay is intermittant, it is located in the center console above the power pack port side.

Let me know how you go on.

Regards
Pete

[FRED-E]

Did you take out the throttle micro switches at dual warning unit??
.... No they were disconnected at the engines

As you operate the squat switch can you hear a relay operate in the center console?
.... Yes I can hear the relay (does this relay do the same thing as the solenoid for the up/down lever on my 337B)

If this relay does not energise when the squat switch is operated the horn will sound. So it does sound like this relay is intermittant, it is located in the center console above the power pack port side.

I will check that relay this week.
Thanks again
Fred N358

[Pete Somers]

Fred

Disconnecting the micro switches at the engines does not prove that the wiring in the engine bays are ok, could be a intermittant short in there when the engine is running, remember this wiring is 30 years old and has put up with a lot in the bays.

The squat switch operates the HYD control valve to stop retraction on the ground, unlike the the old 337 where a solenoid goes across to stop you from lifting the U/C lever.
On your 337G if you put the U/C switch to up on the ground the horn would sound to warn you have done this.

The best way to check all the switches would be to go to pin 4 white wire on the dual voltage unit with a DVM and operate both the squat and the throttle switches. You could even megger the wires thru WITH THEM DISCONNECTED AT BOTH ENDS to see if you have a wire that is rubbed thru somewhere.

Regards
Pete

[FRED-E]

" pin 4 white wire on the dual voltage unit "

I will check this out.
Thanks again Pete
Fred N358