D3687A  D3975D
pinA9 ------------------pinE5 pinB9 ------------------pinF5

(d)  For the right ADIRU, do a wiring check between these pins of connectors D3693A, D3975A, and D3975E:
D3693A  D3975A
pinA5 ------------------pinJ15 pinB5 ------------------pinK15
D3693A  D3975E
pinA5 ------------------pinC5 pinB5 ------------------pinD5

(e)  If you find a problem with the wiring, then do these steps: 1) Repair the wiring. 2) Re-install the DEU 2. To install it, do this task: Display Electronic Unit Installation,
AMM TASK 31-62-21-400-801. 3) Re-install the left and right ADIRUs. To install them, do this task: Air Data Inertial Reference Unit Installation, AMM TASK 34-21-01-400-801. 4) If the observed fault does not show on the first officer’s EFIS display, then you corrected the fault.
-------------------------END OF TASK ---------------------------
829.  Ground Crew Call Horn Sounds -Fault Isolation
A.  Description
(1)  
This task is for the observed fault:

(a)  Ground crew call horn sounds continuously.

(2)  
Under normal operation, the ground crew call horn sounds when air data inertial reference unit (ADIRU) has one of these condition:

*
no equipment cooling

*
no AC power and operates on DC power

(3)  
This fault is for ground crew call horn sounds continuously when there is equipment cooling and ADIRU is operated on AC power.

B.  Possible Causes
(1)
Integrated flight system accessory unit (IFSAU), M1474

(2)  
Air supply low flow detector, M1915

(3)  
Air exhaust low flow detector, M100

(4)  
Left ADIRU, M1749 or Right ADIRU, M1752

(5)  
IRS Master Caution Unit, M1206

(6)
Wiring problem

EFFECTIVITY

34-21 TASKS 828-829
SIL ALL
Page 261 D633A103-SIL Oct 15/2008

C.  Circuit Breakers
(1)  These are the primary circuit breakers related to the fault:
CAPT Electrical System Panel, P18-1
Row Col Number Name
E 5 C01009 ADIRU LEFT DC

F/O Electrical System Panel, P6-1
Row Col Number Name
C 17 C01010 ADIRU RIGHT DC

D.  Related Data
(1)
(SSM 34-21-11)

(2)
(WDM 34-21-11)

(3)
(WDM 31-62-11)

E.  Initial Evaluation
(1)  
Make sure the equipment cooling fans are on.

(2)  
Make sure that these circuit breakers are closed:

CAPT Electrical System Panel, P18-1
Row Col Number Name
E 7 C01007 ADIRU LEFT AC

F/O Electrical System Panel, P6-1
Row Col Number Name
C 14 C01008 ADIRU RIGHT AC

(3)  
Make sure the ON DC lights on the mode select unit (MSU) are off.

(4)  
If the ground crew call horn does not sound, then there was an intermittent fault.

(5)  
If the ground crew call horn sounds continuously, then do the Fault Isolation Procedure below.

NOTE: You can open the ADIRU DC circuit breakers to temporarily turn off the ground crew call horn. The MSU will show DC FAIL for the ADIRU that was turned off.
F. Fault Isolation Procedure
(1)  
Do
the
left
and
right
ADIRU
BITE
procedures
(34-21
TASK
801).

(a)  
If there is a fault message that relates to the ADIRU internal fault, then go to the FIM task to clear that message.

(b)  
After you clear the ADIRU fault message, if the ground crew call horn does not sound, then you corrected the fault.

(c)  
After you clear the ADIRU fault message, if the ground crew call horn continues to sound, then continue.
　
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