Difference between System Test Requirements and Switch Position - EPSU 10WL

TASK 33-51-00-810-820-A
Difference between System Test Requirements and Switch Position - EPSU 10WL

1. Possible Causes

EMER EXIT LT switch 4WL
wiring
EMER pushbutton switch

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 33-51-00-710-001	Operational Test of the Emergency Lights
ASM 335101

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 33-51-00-710-087-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 33-51-00-810-095-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 33-51-00-810-096-A ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) EMER EXIT LT SW/FAP PB/EPSU(10WL)FWD L:
(a) Make sure that on the panel 25VU:

the EMER EXIT LT switch 4WL is in the OFF position,
the EMER EXIT LT OFF light 5WL is on.

1 If the fault continues:

replace the EMER EXIT LT switch 4WL.

2 If the fault continues:

check and repair the wiring between:
EPSU 10WL pin -D and EMER EXIT LT switch 4WL pin 3C,
EPSU 10WL pin A and EMER EXIT LT switch 4WL pin 3B,
EPSU 10WL pin B and EMER EXIT LT switch 4WL pin 2B ASM 335101.

3 If the fault continues:

make sure that the EMER pushbutton switch on the Flight Attendant Panel (FAP) 120RH operates correctly.

4 If the fault continues:

check and repair the wiring between:
EPSU 10WL pin -I and DEU-B 300RH1 connector B pin 29,
EPSU 10WL pin -P and DEU-B 300RH1 connector B pin 31,
EPSU 10WL pin X and DEU-B 300RH1 connector B pin 30 ASM 335101.

5 If the fault continues:

do the trouble shooting procedures for the FAP.

Subtask 33-51-00-710-088-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

5. Close-up
Subtask 33-51-00-860-077-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