(3)
Replace the IRS Master Caution Unit, M1206, on the P61 sidewall panel.
These are the tasks:
AMM TASK 34-21-07-000-801,
AMM TASK 34-21-07-400-801.

(a)  
If the ILS light does not show on the IRS Mode Select Unit when the RECALL annunciator on the IRS Master Caution Unit is pushed, then you corrected the fault.

(b)  
If the ILS light shows on the IRS Mode Select Unit when the RECALL annunciator on the IRS Master Caution Unit is pushed, then continue.

(4)  
Do this check of the wiring:

EFFECTIVITY SIL ALL  34-31 TASK 820 
D633A103-SIL BOEING PROPRIETARY -Copyright # Unpublished Work -See title page for details  Page 232 Jun 15/2010 

(a)  
Remove the IRS Mode Select Unit. To remove it, do this task: AMM TASK 34-21-03-000-801.

(b)  
Remove the MMR. To remove it, do this task: AMM TASK 34-31-42-000-801.

(c)  
Remove the IRS MCU. To remove it, do this task: AMM TASK 34-21-07-000-801.

(d)  
Do a continuity check between the MMR and the IRS MCU:

IRS MCU MMR CONNECTOR CONNECTOR D2269 D10719B
pin7 -------------------pinG1 pin10 -------------------pinH1
D2271  D10721B
pin7 -------------------pinG1 pin10 -------------------pinH1

(e) Do a continuity check between the IRS Mode Select Unit and IRS MCU:
IRS MSU IRS MCU CONNECTOR CONNECTOR D2171 D2269
pin19 -------------------pin12

(f)  If there is not continuity, then do these steps: 1) Repair the wiring. 2) Re-install the IRS Mode Select Unit. To install it, do this task: AMM
TASK 34-21-03-400-801. 3) Re-install the MMR. To install it, do this task: AMM TASK 34-31-42-400-801. 4) Re-install the IRS MCU. To install it, do this task: AMM TASK 34-21-07-400-801. 5) If the ILS light does not show on the IRS Mode Select Unit when the RECALL
annunciator on the IRS Master Caution Unit is pushed, then you corrected the fault.
-------------------------END OF TASK ---------------------------
821. GLS Light Stays On Continuously -Fault Isolation
A. Description
(1)  The GLS light shows on the IRS Mode Select Unit.
B. Possible Causes
(1)  
GPS antenna connection (M2102), D2947 or (M2103), D2941.

(2)  
Multi-Mode Receiver (MMR-1), M2104 or (MMR-2), M2105.

(3)  
IRS Mode Select Unit, P5–69.

(4)  
IRS Master Caution Unit, M1206.

C. Circuit Breakers
(1)  These are the primary circuit breakers related to the fault:
CAPT Electrical System Panel, P18-1
Row Col Number Name
A 2 C01479 RADIO NAVIGATION MMR 1

EFFECTIVITY

34-31 TASKS 820-821
SIL ALL
Page 233 D633A103-SIL Jun 15/2010

F/O Electrical System Panel, P6-1
Row Col Number Name
A 13 C01480 RADIO NAVIGATION MMR 2

D.  Related Data
(1)
(SSM 34-58-11).

(2)
(SSM 34-58-21).

(3)
(WDM 34-31-11).

(4)
(WDM 34-31-21).

(5)
(WDM 34-58-11).

(6)
(WDM 34-58-21).

E.  Initial Evaluation
(1)  Do
this
task:
ILS
or
Multi-Mode
Receiver
BITE
Procedure,
34-31
TASK
801

(a)  
If the GLS light shows on the IRS Mode Select Unit, then do the Fault Isolation Procedure below.

(b)  
the GLS light does not show on the IRS Mode Select Unit, then there was an intermittent fault.

F. Fault Isolation Procedure
(1)  If LOC and G/S Flags are shown on both or either the Captain’s and F/O’s Displays, then do these tasks:
LOC
And
G/S
Flags
Show
　
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