With the ignition in either the Accessories position or the On position, DTC 40 will set to indicate that the radio has not received any data from the BCM for more than 10 seconds. This does not necessarily mean the radio has a fault, it usually indicates that the radio has been in operation on a workbench and the bus has not been connected.

If DTC 40 is set, refer to Diagnostic Starting Point - Data Link Communications in Data Link Communications for further diagnosis.