Failure of the EXIT Sign controlled by EPSU 14WL

TASK 33-51-00-810-863-A
Failure of the EXIT Sign controlled by EPSU 14WL

1. Possible Causes

EXIT MARKING SIGN [46WL]
EXIT SIGN [55WL]
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 33-51-00-710-001	Operational Test of the Emergency Lights
AMM 33-51-00-710-007	Operational Test of the Emergency Lighting in the Cabin with the 'LIGHT EMER' Pushbutton Switch
ASM 335102
AMM 33-51-16-000-001	Removal of the Emergency Exit Sign
AMM 33-51-16-400-001	Installation of the Emergency Exit Sign
AMM 33-51-17-000-001	Removal of the Emergency Exit Location-Sign
AMM 33-51-17-400-001	Installation of the Emergency Exit Location-Sign

3. Fault Confirmation

CAUTION: DO NOT USE THE TEACH-IN PROCEDURE AS AN ALTERNATIVE FOR TROUBLESHOOTING. A TEACH-IN PROCEDURE IS NOT A RESET PROCEDURE. BEFORE YOU DO A TEACH-IN PROCEDURE, MAKE SURE THAT YOU CORRECTED ALL FAILURES. IF YOU DO NOT OBEY THIS, FAILURES CAN CAUSE A MALFUNCTION OF THE CABIN EMERGENCY LIGHTING SYSTEM.

Subtask 33-51-00-710-171-A ** ON A/C NOT FOR ALL

A. Do the operational test of the emergency lights with the MCDU AMM 33-51-00-710-001.

4. Fault Isolation
Subtask 33-51-00-810-185-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 33-51-00-810-186-A ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EXIT SIGNS/EPSU(14WL)MID R:

Do the operational test of the emergency lighting in the cabin with the pushbutton switch AMM 33-51-00-710-007.
During the test, monitor the EXIT MARKING SIGN [46WL] and the EXIT SIGN [55WL] in the mid section of the cabin.
Replace the EXIT MARKING SIGN [46WL] AMM 33-51-16-000-001 and AMM 33-51-16-400-001 if not illuminated.
Replace the EXIT SIGN [55WL] AMM 33-51-17-000-001 and AMM 33-51-17-400-001 if not illuminated.

(a) If the fault continues:

Do a check and repair the wiring between:
EPSU pin R and the EXIT MARKING SIGN [46WL] pin 3.
EPSU pin N and the EXIT SIGN [55WL] pin 3.
EXIT MARKING SIGN [46WL] pin 1 and GND.
EXIT SIGN [55WL] pin 1 and GND ASM 335102.

Subtask 33-51-00-710-172-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

5. Close-up
Subtask 33-51-00-860-118-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:32:12 UTC