The OFF Legend of the GPWS/G/S MODE Pushbutton Switch Does not Come on

TASK 34-48-00-810-821-A
The OFF Legend of the GPWS/G/S MODE Pushbutton Switch Does not Come on

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
AMM 33-10-00-000-002	Removal of the Bulbs and the Body of a Pushbutton Switch in the Cockpit
AMM 33-10-00-400-002	Installation of the Bulbs and the Body of a Pushbutton Switch in the Cockpit
ASM 344801

3. Fault Confirmation
Subtask 34-48-00-860-053-A

A. Job Set-Up
(1) Aircraft Maintenance Configuration
(a) Energize the aircraft electrical circuits
AMM 24-41-00-861-002.

Subtask 34-48-00-865-051-A

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	LIGHTING/ANN LT SPLY/XFMR/BUS 1	26LP	X04

Subtask 34-48-00-710-064-A

C. Test
On the GPWS section of panel 21VU, push the GPWS/G/S MODE pushbutton switch and make sure that the OFF legend comes on.

4. Fault Isolation
Subtask 34-48-00-810-073-A

A. If the OFF legend of the GPWS/G/S MODE pushbutton switch stays off:

on the panel 25VU, set the INT LT/ANN LT switch to TEST and do a check to see if the OFF legend comes on.

(1) If the OFF legend comes on:

do a check and repair the wiring of the GPWS/G/S MODE pushbutton switch (11WZ) from pin A/A1 to the ground point ASM 344801.

(2) If the OFF legend does not come on:

(a) If the fault continues:

do a check and repair the wiring of the GPWS/G/S MODE pushbutton switch (11WZ) from pin A/4 to pin A/A3 ASM 344801.

Subtask 34-48-00-710-065-A

B. Do the test given in Para. 3.C.

5. Close-up
Subtask 34-48-00-860-054-A

A. Put the aircraft back to its initial configuration.
(1) De-energize the aircraft electrical circuits
AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:33:15 UTC