Failure of the Emergency Lights controlled by EPSU 10WL

TASK 33-51-00-810-828-A
Failure of the Emergency Lights controlled by EPSU 10WL

1. Possible Causes

LIGHT-EMERGENCY, CABIN [20WL]
LIGHT-EMERGENCY, CABIN [21WL]
LIGHT EMERGENCY [200WL]
LIGHT EMERGENCY [202WL]
wiring
LIGHT EMERGENCY [201WL]

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 335101
AMM 33-51-11-000-001	Removal of the Cabin Emergency Lights
AMM 33-51-11-400-001	Installation of the Cabin Emergency Light

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 33-51-00-710-101-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 33-51-00-810-109-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 33-51-00-810-110-B ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EMER LT/EPSU(10WL)FWD L:

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 LIGHT-EMERGENCY, CABIN [20WL] and LIGHT-EMERGENCY, CABIN [21WL] above the FWD cabin doors and the LIGHT EMERGENCY [200WL] and LIGHT EMERGENCY [202WL] on the cabin ceiling.
Replace the LIGHT-EMERGENCY, CABIN [20WL] and/or LIGHT-EMERGENCY, CABIN [21WL] AMM 33-51-11-000-001 and AMM 33-51-11-400-001 if not illuminated.
Replace the LIGHT EMERGENCY [200WL] and/or LIGHT EMERGENCY [202WL] AMM 33-51-11-000-001 and AMM 33-51-11-400-001 if not illuminated.

(a) If the fault continues:

Do a check and repair the wiring between:
EPSU 10WL pin E and the LIGHT-EMERGENCY, CABIN [20WL] pin 3.
LIGHT-EMERGENCY, CABIN [20WL] pin 1 and GND.
EPSU 10WL pin E and the LIGHT EMERGENCY [202WL] pin 3.
LIGHT EMERGENCY [202WL] pin 1 and GND.
EPSU 10WL pin G and the LIGHT-EMERGENCY, CABIN [21WL] pin 3.
LIGHT-EMERGENCY, CABIN [21WL] pin 1 and GND.
EPSU 10WL pin G and the LIGHT EMERGENCY [200WL] pin 3.
LIGHT EMERGENCY [200WL] pin 1 and GND ASM 335101.

Subtask 33-51-00-810-110-D ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EMER LT/EPSU(10WL)FWD L:

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 LIGHT-EMERGENCY, CABIN [20WL] and the LIGHT-EMERGENCY, CABIN [21WL] above the FWD cabin doors and the LIGHT EMERGENCY [201WL] on the cabin ceiling.
Replace the LIGHT-EMERGENCY, CABIN [20WL] and/or LIGHT-EMERGENCY, CABIN [21WL] AMM 33-51-11-000-001 and AMM 33-51-11-400-001 if not illuminated.
Replace the LIGHT EMERGENCY [201WL] AMM 33-51-11-000-001 and AMM 33-51-11-400-001 if not illuminated.

(a) If the fault continues:

Do a check and repair the wiring between:
EPSU 10WL pin E and the LIGHT-EMERGENCY, CABIN [20WL] pin 3.
LIGHT-EMERGENCY, CABIN [20WL] pin 1 and GND.
EPSU 10WL pin E and the LIGHT EMERGENCY [201WL] pin 3.
LIGHT EMERGENCY [201WL] pin 1 and GND.
EPSU 10WL pin G and the LIGHT-EMERGENCY, CABIN [21WL] pin 3.
LIGHT-EMERGENCY, CABIN [21WL] pin 1 and GND ASM 335101.

Subtask 33-51-00-710-102-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

5. Close-up
Subtask 33-51-00-860-084-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:32:09 UTC