Quiescent Current Control Module (QCCM)
The Quiescent Current Control Module (QCCM) is located in the right side of the luggage compartment adjacent to the RJB, behind the trim panel.
An addition to the BMS and using signals already transmitted by the BMS control module, the QCCM cuts the power supply to other non-essential control modules to avoid excessive discharge of the battery. The power supplies are cut by opening the contacts of relays internally within the QCCM. The systems supplied via the QCCM are the audio/entertainment systems and the climate control systems.
The QCCM in conjunction with the BCM/GWM assembly, monitor and control the systems power supply to prevent unnecessary battery drain due to the control modules are staying awake after the vehicle electrical system has been shut down.
The system comprises three components:
- The BMS control module
- The BCM/GWM assembly
- The QCCM.
The BMS checks the battery health by analyzing battery quiescent current, battery current drain or state of charge, and determines if any action is required to protect the battery. If action is required this is communicated to the BCM/GWM assembly. The BCM/GWM assembly control logic uses this information to determine if action is required to assist the battery protection. The QCCM control software is contained within the BCM/GWM assembly. The QCCM receives open and close command messages from the BCM/GWM assembly via the LIN bus and reacts accordingly.
The system will be set in 'Transit mode' on delivery. 'Transit mode' has no QCCM operation and the relays remain closed. Therefore battery drain could occur and the system will not react to it. The PDI process requires that the system have to be set from 'Transit mode' to 'Normal mode', which enables the QCCM operation before handing over the vehicle to the customer.
The QCCM has a routine to clean the relay contacts if required. This routine is performed using the Jaguar approved diagnostic system and, if unsuccessful, the unit will require replacement.