EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 21-58-00
 ALL  ú ú 06 Page 527 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 865-034
 (30)
 Do the "Put the Air/Ground Relay System Back in the Ground Mode" task (Ref 32-09-02/201).

 S 735-023

 (31)
 Do a test of the overheat switch with the airplane in the ground mode.

 (a)  
Remove the electrical connector DS1977 from the overheat switch.

 (b)  
Install a jumper between pins 1 and 2 of the electrical connector DS1977.

 (c)  
Make sure that after 60 seconds the ground crew call horn

 sounds and these messages are shown: ~.................................................. | EICAS Caution | EQUIP COOLING | .................................................... | EICAS Status | EQUIPMENT TEMP | 2.........................…........................1

 (d)  
Remove the jumper from the electrical connector DS1977.

 (e)  
Make sure the ground crew call horn stops.

 (f)  
Make sure these messages are not shown:
 ~..................................................
 | EICAS Caution | EQUIP COOLING |
 ....................................................
 | EICAS Status | EQUIPMENT TEMP |
 2.........................…........................1

 S 865-035
 WARNING: YOU MUST CAREFULLY FOLLOW THE STEPS IN THE SPECIFIED TASK TO
_______ PUT THE AIR/GROUND RELAY SYSTEM IN THE AIR MODE. FAILURE TO FOLLOW THE STEPS CORRECTLY CAN CAUSE THE AUTOMATIC OPERATION OF THE AIRPLANE SYSTEMS. THIS CAN CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
 (32)
 Do the "Put the Air/Ground Relay System in the Air Mode" task (Ref 32-09-02/201).

 S 735-024

 (33)
 Do a test of the overheat switch with the airplane in the air mode.

 (a)  
Install a jumper between pins 1 and 2 of the electrical connector DS1977.

 (b)  
Make sure that after 40 seconds these messages are shown: ~.................................................. | EICAS Caution | EQUIP COOLING | .................................................... | EICAS Status | EQUIPMENT TEMP | 2.........................…........................1

 (c)  
Make sure the ground crew call horn does not operate.

 (d)  
Remove the jumper from the electrical connector DS1977.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 21-58-00
 ALL  ú ú 09 Page 528 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 (e)  
Make sure that these messages are not shown:
 ~..................................................
 | EICAS Caution | EQUIP COOLING |
 ....................................................
 | EICAS Status | EQUIPMENT TEMP |
 2.........................…........................1

 (f)  
Install the electrical connector DS1977 on the overheat switch.

 S 865-036
 (34)
 Do the "Put the Air/Ground Relay System Back in the Ground Mode" task (Ref 32-09-02/201).

 S 735-025

 (35)
 Test low flow detectors.

 (a)  
Remove electrical connector DM7933 from flight deck low flow detector.

 (b)  
Install a jumper between pins 2 and 3 of electrical connector DM7933.

 (c)  
Check that the following messages are displayed (allow 30

 seconds): ~.................................................. | EICAS caution | EQUIP COOLING | .................................................... | EICAS status | FLT DK LOW FLOW | 2.........................…........................1

 (d)  
Check that ground crew call horn is not activated.

 (e)  
Remove jumper from electrical connector DM7933.

 (f)  
Check that the following messages are not displayed:
　
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