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.
CAUTION:
Always turn ignition off before disconnecting or connecting any control module connector. Failure to do so could result in damage to control module.
NOTE:
Ensure vehicle being tested has a fully charged battery. If it does not, false DTCs or error messages may occur.
NOTE:
For component location, see appropriate illustration under COMPONENT LOCATIONS
. For terminal identification, see appropriate illustration under CONNECTOR IDENTIFICATION
. For circuit and wire color identification, see WIRING DIAGRAMS
. For component removal and installation procedures, see appropriate component under REMOVAL & INSTALLATION
.
Testing:
- Turn ignition off. Connect DRBIII(R) to DLC. Turn ignition on. Using the DRBIII(R), read HVAC DTCs. Does the DRBIII(R) display additional HVAC DTCs? If yes, return to DIAGNOSTIC TROUBLE CODE DEFINITIONS and perform appropriate DTC test. If no, replace A/C-Heater Control Module. Perform BODY VERIFICATION TEST under VERIFICATION TESTS.