The diagnostic trouble code (DTC) B101E:4B in 2011 Chevrolet Equinox and GMC Terrain models often indicates a problem with the heating, ventilation, and air conditioning (HVAC) system. This code specifically points to a calibration issue within the HVAC control module. While sometimes no codes are present, erratic HVAC behavior can manifest as intermittent operation, unwanted temperature changes, or the A/C unexpectedly turning off and on.
This intermittent nature can make diagnosis challenging. Technicians might find no DTCs or encounter B101E:4B, suggesting a missing or incorrectly set calibration, possibly after an HVAC actuator learning procedure. Often, the root cause lies in a poor connection within the actuator wire harness.
If the HVAC malfunction is consistent, such as a non-functional temperature mode or incomplete sweep, standard diagnostic procedures should be followed, potentially leading to a faulty actuator replacement. However, if the issue is intermittent and connections at the HVAC module and actuators appear normal, the problem likely resides in the wiring.
In such cases, replacing the wire harness connecting the HVAC module to the actuators and evaporator sensor is recommended. Applying dielectric grease, as outlined in Service Bulletin #09-06-03-004D, to prevent fretting corrosion is crucial during this repair. This comprehensive approach addresses the underlying connectivity issue, resolving the intermittent HVAC problems associated with DTC B101E:4B in these vehicles.
