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Symptom: LOOPBACK TEST FAILURE (ACTIVE) When Monitored and Set Condition: 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 POSSIBLE CAUSES CHECK FOR ADDITIONAL HVAC DTCS A/C - HEATER CONTROL MODULE TEST ACTION APPLICABILITY 1 Turn the ignition on. t, read HVAC DTCs. Does the DRBIII t display additional HVAC DTCs? All Yes → Return to the symptom list and choose the symptom(s). Perform BODY VERIFICATION TEST - VER 1. No → Replace the A/C - Heater Control Module in accordance with the Service Information. 221 HEATING & A/C |