Failure of the Emergency Lights controlled by EPSU 12WL

TASK 33-51-00-810-853-A
Failure of the Emergency Lights controlled by EPSU 12WL

1. Possible Causes

LIGHT EMERGENCY [201WL]
LIGHT EMERGENCY [204WL]
wiring
CABIN EMERGENCY LIGHTS [36WL]
LIGHT EMERGENCY [206WL]
CABIN EMERGENCY LIGHT (209WL)

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 33-51-00-710-150-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 33-51-00-810-162-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 33-51-00-810-163-E ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EMER LT/EPSU(12WL)EMER 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 LIGHT EMERGENCY [201WL] and LIGHT EMERGENCY [204WL] on the cabin ceiling.
Replace the LIGHT EMERGENCY [201WL] and/or LIGHT EMERGENCY [204WL] 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 12WL pin E and the LIGHT EMERGENCY [201WL] pin 3.
LIGHT EMERGENCY [201WL] pin 1 and GND.
EPSU 12WL pin E and the LIGHT EMERGENCY [204WL] pin 3.
LIGHT EMERGENCY [204WL] pin 1 and GND ASM 335101.

Subtask 33-51-00-810-163-F ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EMER LT/EPSU(12WL)EXT 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 CABIN EMERGENCY LIGHTS [36WL] above the mid cabin doors and the LIGHT EMERGENCY [206WL] and CABIN EMERGENCY LIGHT (209WL) on the cabin ceiling.
Replace the CABIN EMERGENCY LIGHTS [36WL] AMM 33-51-11-000-001 and AMM 33-51-11-400-001 if not illuminated.
Replace the LIGHT EMERGENCY [206WL] and/or CABIN EMERGENCY LIGHT (209WL) 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 12WL pin E and the CABIN EMERGENCY LIGHTS [36WL] pin 3.
CABIN EMERGENCY LIGHTS [36WL] pin 1 and GND.
EPSU 12WL pin E and the LIGHT EMERGENCY [206WL] pin 3.
LIGHT EMERGENCY [206WL] pin 1 and GND.
EPSU 12WL pin G and the CABIN EMERGENCY LIGHT (209WL) pin 3.
CABIN EMERGENCY LIGHT (209WL) pin 1 and GND ASM 335101.

Subtask 33-51-00-710-151-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

5. Close-up
Subtask 33-51-00-860-108-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:32:11 UTC