DMU Receives No Data from the ACARS-MU or ATSU

TASK 31-36-00-810-835-A
DMU Receives No Data from the ACARS-MU or ATSU

1. Possible Causes

wiring
ATSU [1TX1]
DMU [1TV]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 31-36-00-710-001	Test of the DMU
ASM 313605
AMM 31-36-34-000-001	Removal of the Data Management Unit (DMU)
AMM 31-36-34-400-001	Installation of the Data Management Unit (DMU)
AMM 46-21-00-710-001	Operational Test of the ATSU

3. Fault Confirmation
Subtask 31-36-00-740-096-B ** ON A/C NOT FOR ALL

A. Do the DMU (1TV) fault monitoring test AMM 31-36-00-710-001.

NOTE: Make sure that the circuit breakers 1TV, 1TX1 on the panel 121VU are closed during the test.

4. Fault Isolation
Subtask 31-36-00-810-075-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message:

NO ACARS DATA, or
ACARS COMMUNIC FAIL

(1) Do the operational test of the ATSU AMM 46-21-00-710-001.

(a) If the test gives a different maintenance message, you can find the related trouble shooting procedure in the applicable Page Block 201.

(2) If the fault continues:

do a check and repair the wiring from the ATSU [1TX1] to the DMU [1TV] ASM 313605:

ATSU Connector AA/1E to DMU Connector AB/5J
ATSU Connector AA/1F to DMU Connector AB/5K
ATSU Connector AB/8A to DMU Connector AB/11J
ATSU Connector AB/8B to DMU Connector AB/11K

(3) If the fault continues:

replace the DMU (1TV) AMM 31-36-34-000-001 and AMM 31-36-34-400-001.

Subtask 31-36-00-740-097-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:30:04 UTC