Loopback Test Failure (Active)

Test 1:

SYMPTOM
LOOPBACK TEST FAILURE (ACTIVE) - MTC

WHEN MONITORED
When the A/C - Heater Control Module executes an internal loopback test.

SET CONDITION
If the A/C - Heater Control Module fails to send a message, or none of the expected messages arrive for 5 seconds, an internal loopback test is executed. If the internal loopback test fails, the DTC will set.

POSSIBLE CAUSES
- Additional code(s) present
- A/C - Heater control module