(c)  
AIRPLANES WITH TCAS; The WEU also receives digital input signals from the TCAS on the ARINC 429 digital bus.

 (d)  
The WEU modules provide analog discrete signals to the loudspeakers. They also provide discrete signals to turn on the master warning lights, the discrete warning light, and to the EICAS computers.

 (e)  
The Landing configuration warning module also provides discrete signals to turn on the SPEEDBRAKES light.

 (f)  
The WEU monitor circuits continuously perform operational checks of the input and output power supply circuits. The fault balls on the front of the WEU come on when a fault is detected.

 (g)  
The warning visual indications consist of the master and CONFIG warning lights. The aural indications are the fire bell and the siren.

 (h)  
The red master WARNING lights come on continuously when level A warnings are displayed on the EICAS display unit. The lights come on for 16 level A warnings associated with five conditions. These are fire, overspeed, autopilot disconnect, and takeoff and landing configuration warnings. There is a one-half second delay for the autopilot disconnect warnings. The light contains a manual reset switch. Pressing the light will provide a ground signal to the master warning module to extinguish the light. The warning circuit is then rearmed for the next warning.

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 (i)  The CONFIG light is turned on by either the takeoff or landing
 configuration warning function.
 (j)  The fire bell comes on and operates on an intermittent cycle
 during fire warnings. The fire bell is repeated until the
 warning is cancelled. The bell may be cancelled by pressing
 either master warning light, or cancelled by pulling one of the
 engine or the APU fire handles or by setting the cargo
 compartment fire select switch to the FWD or AFT position.
 Wheel well fire warnings may be cancelled by lowering the nose
 gear.
 (k)  When the nose wheel oleo switch is extended during takeoff, the
 master WARNING lights and the fire bell are inhibited. At this
 time, a 20-second delay timer is also initiated. The inhibit
 function is cancelled after 20 seconds, or when the radio
 altitude is greater than 400 feet. The stored warnings will
 turn on the WARNING lights as soon as the inhibit function is
 cancelled.
 (l)  The siren comes on during the configuration, overspeed, cabin
　
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