Loss of the MMR2 Data Input to the ATC/Mode S Transponder 2

TASK 34-52-00-810-846-A
Loss of the MMR2 Data Input to the ATC/Mode S Transponder 2

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 34-36-31-000-001	Removal of the ILS Receiver
AMM 34-36-31-400-001	Installation of the ILS Receiver
AMM 34-52-00-740-004	BITE Test of the ATC
ASM 345202
AMM 34-52-33-000-001	Removal of the ATC/Mode S Transponder
AMM 34-52-33-400-001	Installation of the ATC/Mode S Transponder

3. Fault Confirmation
Subtask 34-52-00-865-054-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	COM NAV/ATC/2	5SH2	K07
121VU	COM NAV/MMR/2	42RT2	L07

Subtask 34-52-00-860-050-A ** ON A/C NOT FOR ALL

B. Do a reset of the ATC/Mode S transponder 2 (1SH2) as follows:
On the rear C/B panel 121VU:

Subtask 34-52-00-740-128-A ** ON A/C NOT FOR ALL

C. Test
(1) Do the BITE test of the ATC2 AMM 34-52-00-740-004.

4. Fault Isolation
Subtask 34-52-00-810-105-C ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message MMR2(40RT2)/ATC2(1SH2):

(1) If the fault continues:

(a) If the fault continues:

remove the ATC/Mode S transponder 2.
remove the MMR2.
do a check and repair the wiring from the ATC/Mode S transponder 2 to the MMR2: from pins AB/4C, 4D to pins AB/9E, 9F (GNSS OUT3) ASM 345202.
install the ATC/Mode S transponder 2.
install the MMR2.

Subtask 34-52-00-740-129-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:33:25 UTC