Loopback Test Failure (Active)

Test 1:

SYMPTOM
LOOPBACK TEST FAILURE (ACTIVE)

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
- Check for additional HVAC DTCs
- A/C - heater control module