Sign - Fault in the FASTEN SEAT BELT sign

TASK 23-73-00-810-840-A
Sign - Fault in the FASTEN SEAT BELT sign

1. Possible Causes

NS-FSB 531RH sign lamp
NS-FSB sign
PISA
wiring
PCB 2038VU
DEU-A
SEAT BELTS switch
DIR-CIDS, 1 [101RH]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-73-00-710-034	Operational Test of the Cabin Signs through the MCDU
AMM 23-73-00-710-035	Operational Test of the Cabin LED lamps through the MCDU
AMM 23-73-00-740-005	BITE-Test of the Cabin Intercommunication Data System (CIDS) through the CFDS
ASM 237302
ASM 237313
ASM 237314
AMM 23-73-34-000-001	Removal of the CIDS Director
AMM 23-73-34-400-001	Installation of the CIDS Director
AMM 23-73-41-000-001	Removal of the Passenger Interface and Supply Adapter (602RH)
AMM 23-73-41-400-001	Installation of the Passenger Interface and Supply Adapter (602RH)
AMM 23-73-46-000-001	Removal of the Decoder/Encoder Unit A (200RH)
AMM 23-73-46-400-001	Installation of the Decoder/Encoder Unit A (200RH)
AMM 23-73-49-000-001	Removal of the Printed Circuit Board
AMM 23-73-49-400-001	Installation of the Printed Circuit Board
AMM 23-73-63-000-001	Removal of the No Smoking/Fasten Seat Belt sign from the Passenger Service Information Unit and the C/B panels 2000VU/2001VU
AMM 23-73-63-000-002	Removal of the No Smoking/Fasten Seat Belt sign from the cabin
AMM 23-73-63-400-001	Installation of the No Smoking/Fasten Seat Belt sign in the Passenger Service Information Unit and the C/B panels 2000VU/2001VU
AMM 23-73-63-400-002	Installation of the No Smoking/Fasten Seat Belt sign in the cabin

3. Fault Confirmation
Subtask 23-73-00-710-058-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the CIDS1/SIGN LAMP test through the CFDS AMM 23-73-00-710-034.

NOTE: An erroneous class 3 fault message will be recorded for each LED NS/FSB and RTS sign (without bulbs), if the test of the related signs is not deactivated in the CAM.

(2) Set the SEAT BELTS switch to the ON position and make sure that the lamp comes on.

Subtask 23-73-00-710-058-B ** ON A/C NOT FOR ALL

A. Test
(1) Do the CIDS Interface and Power-Up Test via the CFDS AMM 23-73-00-740-005.
(2) Do the Operational Test of the Cabin LED Lamps via the CFDS AMM 23-73-00-710-035.

4. Fault Isolation
Subtask 23-73-00-810-059-A

A. If the test gives a different maintenance message, do the trouble shooting procedure related to the maintenance message.

Subtask 23-73-00-810-166-A ** ON A/C NOT FOR ALL

B. If the CIDS1/SIGN LAMP test gives the maintenance message FSB LAMP XX and a lamp does not come on:

NOTE: XX identifies the location of the faulty unit:

SR: ..L/R,
FWD L/R, 1/2,
AFT L/R, 1/2,

replace the related NS-FSB 531RH sign lamp AMM 23-73-63-000-001 and AMM 23-73-63-400-001.

Subtask 23-73-00-810-167-A ** ON A/C NOT FOR ALL

C. If the fault continues:

do a check for 28 VDC at pins P and K on the PCB 2038VU ASM 237313 and ASM 237314.

(1) If there is approx. 28 VDC:

do a check and repair the wiring if necessary between the:
NS-FSB sign and the PCB 2038VU.

(a) If there is no 28 VDC:

do a check for 28 VDC at pins C and N on the PCB 2038VU.

1 If there is approx. 28 VDC:

replace the PCB 2038VU AMM 23-73-49-000-001 and AMM 23-73-49-400-001.

(2) If there is no 28 VDC:

do a check for 28 VDC at the related DEU-A between the related pairs of connectors given below:
Connectors C/18 and C/22 or
Connectors C/19 and C/24 or
Connectors C/20 and C/26 ASM 237313 and ASM 237314.

(a) If there is approx. 28 VDC:

do a check and repair the wiring if necessary between pins C and N on the PCB 2038VU and the related DEU-A pairs of connectors given below:
Connectors C/18 and C/22 or
Connectors C/19 and C/24 or
Connectors C/20 and C/26 ASM 237313 and ASM 237314.

(b) If there is no 28 VDC:

replace the related DEU-A AMM 23-73-46-000-001 and AMM 23-73-46-400-001.

Subtask 23-73-00-810-166-C ** ON A/C NOT FOR ALL

D. If the test confirms the fault:

replace the related NS-FSB sign AMM 23-73-63-000-001 and AMM 23-73-63-400-001 or AMM 23-73-63-000-002 and AMM 23-73-63-400-002.

(1) If the fault continues:

replace the related PISA AMM 23-73-41-000-001 and AMM 23-73-41-400-001.

Subtask 23-73-00-810-167-B ** ON A/C NOT FOR ALL

E. If the fault continues:

do a check and repair if necessary the wiring between the related PISA connector and the NS/FSB sign at the signal names:
FSB 28 VDC OUT
FSB/NS RETURN
ASM 237313
ASM 237314.

Subtask 23-73-00-810-168-A ** ON A/C NOT FOR ALL

F. If the CIDS1/SIGN LAMP test gives the maintenance message FSB LAMP XX, L, R (XX seat row) but the lamps come on:

NOTE: An erroneous class 3 fault message will be recorded for each LED NS/FSB sign (without bulbs), if the test of the related signs is not deactivated in the CAM.

replace the related DEU-A AMM 23-73-46-000-001 and AMM 23-73-46-400-001.

Subtask 23-73-00-810-169-A ** ON A/C NOT FOR ALL

G. If no FSB lamps come on:

do a check of the SEAT BELTS switch and replace it if necessary.

(1) If the fault continues:

do a check and repair the wiring if necessary between the:
DIR-CIDS (101RH) connector AB/E15 and GND of SEAT BELTS switch (191RH) ASM 237302.

Subtask 23-73-00-810-170-A ** ON A/C NOT FOR ALL

H. If the fault continues:

replace the DIR-CIDS, 1 [101RH] AMM 23-73-34-000-001 and AMM 23-73-34-400-001.

Subtask 23-73-00-810-171-A

I. Do the test given in Para. 3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:25:52 UTC