Volume Does Not Increase With Speed

Audio System Symptom Troubleshooting - Volume does not increase with speed

Volume does not increase with speed

NOTE:

- Check the vehicle battery condition first Battery Test.
- Check the connectors for poor connections or loose terminals.

1. Test-drive the vehicle at highway speeds, and monitor if the volume increases.

Does the volume increase?

YES -

Intermittent failure, the system is OK at this time.

NO -

Go to step 2.

2. Verify SVC mode setting in audio unit sound adjustment set-up.

Is the SVC set to off?

YES -

Change setting to SVC MID, and recheck.

NO -

Go to step 3.

3. Do the Self-Diagnostic Function for the vehicle speed pulse indication Audio System Self-Diagnostic Function.

Does self-diagnostic function indicate a VSP signal?

YES -

Substitute a known-good audio unit; with navigation Audio Unit Removal/Installation (With Navigation), without navigation Audio Unit Removal/Installation (Without Navigation), and recheck. If the symptom/indication goes away, replace the original audio unit; with navigation Audio Unit Removal/Installation (With Navigation), without navigation Audio Unit Removal/Installation (Without Navigation).

NO -

- 1 CD type: Go to step 4.
- Except 1 CD type: Check for B-CAN DTCs (communication BUS Line Error) with the HDS and go to the indicated DTC's troubleshooting. If no B-CAN DTCs or communication bus line errors are found, substitute a known-good audio unit; with navigation Audio Unit Removal/Installation (With Navigation), without navigation Audio Unit Removal/Installation (Without Navigation), and recheck. If the symptom/indication goes away, replace the original audio unit; with navigation Audio Unit Removal/Installation (With Navigation), without navigation Audio Unit Removal/Installation (Without Navigation).

4. Turn the ignition switch to LOCK (0).

5. Jump the SCS line with the HDS.

6. Disconnect ECM/PCM connector A (49P).

7. Turn the ignition switch to ON (II).

8. Measure the voltage between ECM/PCM connector A (49P) terminal No. 30 and body ground.





Is there about 5 V?

YES -

Go to step 10.

NO -

Go to step 9.

9. Measure the voltage between audio unit connector A (24P) terminal No. 15 and body ground.





Is there about 5 V?

YES -

Repair an open or a short in the wire between the audio unit and the ECM/PCM.

NO -

Substitute a known-good audio unit Audio Unit Removal/Installation (Without Navigation), and recheck. If the symptom/indication goes away, replace the original audio unit Audio Unit Removal/Installation (Without Navigation).

10. Turn the ignition switch to LOCK (0).

11. Reconnect ECM/PCM connector A (49P).

12. Turn the ignition switch to ON (II).

13. Raise the vehicle on a lift, and rotate the wheels while measuring the voltage between audio unit connector A (24P) terminal No. 15 and body ground.





Does the voltage pulse between 0 V and 5 V as you rotate the wheels?

YES -

Replace the audio unit Audio Unit Removal/Installation (Without Navigation).

NO -

Update the ECM/PCM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM/PCM.