Failure of the Exit Signs controlled by EPSU 12WL

TASK 33-51-00-810-838-A
Failure of the Exit Signs controlled by EPSU 12WL

1. Possible Causes

SIGN-EXIT MARKING [42WL]
ESCAPE HATCH-HANDLE LIGHT [70WL2]
SIGN-EXIT [53WL]
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 33-51-11-000-001	Removal of the Cabin Emergency Lights
AMM 33-51-11-400-001	Installation of the Cabin Emergency Light
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 33-51-00-710-121-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 33-51-00-810-130-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 33-51-00-810-131-A ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EXIT SIGNS/EPSU(12WL)EMER R:

do the Operational Test of the Emergency Lighting in the Cabin by Pushbutton Switch AMM 33-51-00-710-007.
during the test monitor the SIGN-EXIT MARKING [42WL] , ESCAPE HATCH-HANDLE LIGHT [70WL2] and the SIGN-EXIT [53WL] in the CTR section of the cabin.
replace the SIGN-EXIT MARKING [42WL] AMM 33-51-16-000-001 and AMM 33-51-16-400-001 if not illuminated.
replace the ESCAPE HATCH-HANDLE LIGHT [70WL2] AMM 33-51-11-000-001 and AMM 33-51-11-400-001 if not illuminated.
replace the SIGN-EXIT [53WL] 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 N and the ESCAPE HATCH-HANDLE LIGHT [70WL2] pin 3.
EPSU pin N and the SIGN-EXIT [53WL] pin 3.
EPSU pin R and the SIGN-EXIT MARKING [42WL] pin 3.
ESCAPE HATCH-HANDLE LIGHT [70WL2] pin 1 and GND.
SIGN-EXIT [53WL] pin 1 and GND.
SIGN-EXIT MARKING [42WL] pin 1 and GND ASM 335102.

Subtask 33-51-00-710-122-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

5. Close-up
Subtask 33-51-00-860-094-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:32:10 UTC