Mechanic Call Horn Inoperative

TASK 34-11-00-810-867-A
Mechanic Call Horn Inoperative

1. Possible Causes

RELAY-ADIRS ON BAT/GROUND WARN [12FP]
wiring of the ADIRS ON BAT/GROUND WARN relay (12FP)
RELAY-ADIRS LGCIU GND POS [23FP]
wiring of the ADIRS LGCIU ground position relay (23FP)
LGCIU-1 [5GA1]
RELAY-HORN SUPPLY RESET (8WC)
wiring of the horn supply reset relay (8WC)
wiring of the diode module (1160VD)
DIODE MODULE (1160VD)
HORN-MECH CALL [15WC]
RELAY-HORN SUPPLY (4WC)
wiring of the horn supply relay (4WC)
C/B-EIS/HORN/SPLY [2WC]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-42-00-710-001	Operational Test of the Mechanic Call
ASM 234201
AMM 32-31-71-000-001	Removal of the LGCIU
AMM 32-31-71-400-001	Installation of the LGCIU
AMM 34-11-00-710-002	Test of the Monitoring of the ADIRS Power Supply (115VAC-28VDC)
ASM 341101

3. Fault Confirmation
Subtask 34-11-00-710-084-A

A. Test
(1) Do the test of the monitoring of the ADIRS power supply (115VAC-28VDC) AMM 34-11-00-710-002.
(a) Make sure that the mechanic call horn operates and that the ADIRU & AVNCS VENT light comes on:

when the ADIRU1 is de-energized
when the ADIRU2 is de-energized
when the ADIRU3 is de-energized.

4. Fault Isolation
Subtask 34-11-00-810-186-B

A. If during the test:

the mechanic call horn does not operate
the ADIRU & AVNCS VENT light does not come on:
. replace the RELAY-ADIRS ON BAT/GROUND WARN [12FP] .

(1) If the fault continues:

do a check of the wiring of the ADIRS ON BAT/GROUND WARN relay (12FP):
. pin A/2 to the ground point
. pin A/1 to the first terminal block
. pin A/X1 to the first terminal block
. pin A/X2 to ADIRS LGCIU ground position relay (23FP) pin A/A
ASM 341101.

(a) If there is no continuity:

repair the above wiring.

(b) If there is continuity:

replace the RELAY-ADIRS LGCIU GND POS [23FP] .

1 If the fault continues:

do a check of the wiring of the ADIRS LGCIU ground position relay (23FP):
. pin A/1 to the ground point
. pin A/Z to the ground point
. pin A/X to LGCIU (5GA1) pin AA/10A.

a If there is no continuity:

repair the above wirings.

b If there is continuity:

replace the LGCIU-1 [5GA1] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.

Subtask 34-11-00-810-187-A

B. If during the test:

the mechanic call horn does not operate
the ADIRU & AVNCS VENT light comes on:
. do the operational test of the mechanic call AMM 23-42-00-710-001.

(1) If the mechanic call horn operates correctly:

replace the RELAY-HORN SUPPLY RESET (8WC).

(a) If the fault continues:

do a check of the wiring of the horn supply reset relay (8WC):
. pin A/1 to the first terminal block
. pin A/A to diode module (1160VD) pin A/26
ASM 234201 and ASM 341101.

1 If there is no continuity:

repair the above wiring.

2 If there is continuity:

do a check of the wiring of the diode module (1160VD): pin A/11 to the first terminal block ASM 341101.

a If there is no continuity:

repair the above wiring.

b If there is continuity:

replace the DIODE MODULE (1160VD).

(2) If the mechanic call horn does not operate:

replace the HORN-MECH CALL [15WC] .

(a) If the fault continues:

replace the RELAY-HORN SUPPLY (4WC).

1 If the fault continues:

do a check of the wiring of the horn supply relay (4WC):
. pin A/Z to the first terminal block
. pin A/4 to the mechanic call horn (15WC)
. pins A/X and A/B to the circuit breaker (2WC)
ASM 234201.

a If there is no continuity:

repair the above wirings.

b If there is continuity:

replace the C/B-EIS/HORN/SPLY [2WC] .

Subtask 34-11-00-810-188-A

C. If the mechanic call horn does not operate:
(1) Only with the ADIRU1 de-energized:

replace the DIODE MODULE (1160VD).

(a) If the fault continues:

do a check and repair the wiring of the diode module (1160VD):
. pin A/5 to the first terminal block
. pin A/20 to the first terminal block
ASM 341101.

(2) Only with the ADIRU2 de-energized:

replace the DIODE MODULE (1160VD).

(a) If the fault continues:

do a check and repair the wiring of the diode module (1160VD):
. pin A/8 to the first terminal block
. pin A/23 to the first terminal block
ASM 341101.

(3) Only with the ADIRU3 de-energized:

replace the DIODE MODULE (1160VD).

(a) If the fault continues:

do a check and repair the wiring of the diode module (1160VD):
. pin A/7 to the first terminal block
. pin A/22 to the first terminal block
ASM 341101.

Subtask 34-11-00-710-085-A

D. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:32:17 UTC