Constant VRO alarm without initial 'key on beep' - 1989 120 Looper

[benjiboy]

I have confirmed I have a non-functional warning horn and installed a temporary horn for diagnostic duty.

The VRO alarm is going off constantly and I have determined the VRO pump is causing a constant alarm condition because unplugging the 3-wire VRO plug stops the constant alarm.

However, I have never been able to get the system to chirp once at initial key on. The alarm is either constantly on or completely silent so needless to say I'm confused and don't want to rid the VRO system but will not run it without a functioning alarm system...

Any help is appreciated!

 

[Joe Reeves]

(Odd Soundings Of Warning Horn)
(J. Reeves)

Should the warning horn beep constantly when the key is turned to the ON position rather than sounding just a short beep as it should, do the following test.

Remove the TAN wire from the horn. If the constant beeping continues, the horn is faulty, in which case replace it. However, on the other hand, if the beeping stops, something has gone wrong with one of the sensor components at the engine, in which case start disconnecting the TAN wires that are connected to the various components (Heat Sensors, VRO, Vacuum Switch if so equipped, Oil Tank). Disconnecting a unit and having the beeping stop...... you've found the faulty component.

NOTE: The small black plastic horn that has a built in black ground wire...... The TAN wire must be attached to the terminal closest to that black wire. Otherwise weird things will happen.

 

[benjiboy]

Thanks Joe, I think I caught that response in another thread through my searches and appreciate your response. I have replaced my known non-functional horn with a working horn (of a different type, however), disconnected all components and isolated the VRO 'no oil' circuit as the culprit.

What would cause a faulty no oil circuit to constantly sound the alarm? (other than a grounded wire, of course)

 

[Joe Reeves]

A grounded wire (The Tan Wire) would cause the warning horn to sound constantly and steady... not a beeping. If you're sure the circuit of the VRO horn is actually the cause, the cure is to replace the VRO.

 

[benjiboy]

Thanks, I am confident the VRO circuit is the cause as disconnecting the 3-wire VRO harness silences the alarm.