Sign - Info sign at one PSIU does not come on

TASK 23-73-00-810-873-A
Sign - Info sign at one PSIU does not come on

1. Possible Causes

lamps
LIGHT PNL
DEU-A
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-73-00-740-005	BITE-Test of the Cabin Intercommunication Data System (CIDS) through the CFDS
ASM 237313
ASM 237314
ASM 237315
ASM 237316
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 23-73-63-000-001	Removal of the No Smoking/Fasten Seat Belt sign from the Passenger Service Information Unit and the C/B panels 2000VU/2001VU
AMM 23-73-63-400-001	Installation of the No Smoking/Fasten Seat Belt sign in the Passenger Service Information Unit and the C/B panels 2000VU/2001VU

3. Fault Confirmation
Subtask 23-73-00-710-232-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the CIDS BITE test through the CFDS AMM 23-73-00-740-005.

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

(2) In the cockpit, on the overhead panel 25VU (SIGNS):

set the NO SMOKING (190RH) switch to ON,
set the FASTEN SEAT BELT (191RH) switch to ON.

4. Fault Isolation
Subtask 23-73-00-810-520-A ** ON A/C NOT FOR ALL

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

Subtask 23-73-00-810-521-A ** ON A/C NOT FOR ALL

B. If the related NS/FSB info signs do not come on:

do a check for 28 VDC at the related LIGHT PNL pins 1 and 3 ASM 237313 ASM 237314, ASM 237315 and ASM 237316.

(1) If there is approx. 28 VDC and the related NS/FSB sign has lamps:

replace the related lamps .

(a) If the fault continues:

replace the LIGHT PNL AMM 23-73-63-000-001 and AMM 23-73-63-400-001.

(2) If there is no 28 VDC:

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

(a) If the fault continues:

do a check and repair the wiring between the related:
LIGHT PNL pin 1 and DEU-A connector C/22,C/24 or C/26,
LIGHT PNL pin 2 and DEU-A connector C/18,C/19 or C/20,
LIGHT PNL pin 3 and DEU-A connector C/21,C/23 or C/25 ASM 237313 ASM 237314, ASM 237315 and ASM 237316.

Subtask 23-73-00-710-233-A ** ON A/C NOT FOR ALL

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

[Rev.8 from Aug 2018] 2026.04.04 04:25:54 UTC