Test F: The Speed Sensitive Volume Does Not Operate Correctly

PINPOINT TEST F: THE SPEED SENSITIVE VOLUME DOES NOT OPERATE CORRECTLY

Normal Operation
The speed sensitive volume function adjusts the volume based on the vehicle speed sensor (VSS) signal from the instrument cluster. The instrument cluster does not generate the VSS signal; it gateways the signal from the PCM.

DTC U0155 (Lost Communication With Instrument Panel Cluster Control [IC] Module) - sets when the VSS signal is lost for greater than 5 seconds. When the signal is lost, the audio unit turns the speed sensitive volume feature off. The smart junction box (SJB) and electronic automatic temperature control (EATC) module also receive this signal, and should demonstrate symptoms if the VSS signal is lost. If no symptoms are present, this DTC can be ignored, as it may have been set by a low battery voltage condition.

This pinpoint test is intended to diagnose the following:
- Speed sensitive volume setting
- VSS signal concern
- Audio unit

F1-F5: