No Sound Is Heard [Vehicles With Audio Amplifier]
Inspection Procedure 2: No Sound is Heard.CAUTION: Before replacing the ECU, ensure that the power supply circuit, the ground circuit, and the communication circuit are normal. (Check that the voltage is 10 V or more.)
Audio Visual Navigation System Circuit (Part 1):
Audio Visual Navigation System Circuit (Part 2):
COMMENTS ON TROUBLE SYMPTOM
If the audio sound is not output, the audio visual navigation unit, audio amplifier, or power supply circuit of audio amplifier may have a problem, or the option coding information may be inconsistent.
PROBABLE CAUSES
- Malfunctions of audio visual navigation unit
- Malfunction of audio amplifier
- Option coding information inconsistency
- Damaged harness wires and connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Check the audio visual navigation unit operation.
Q: Check the sources from which the sound is not output.
No sound only from radio : Perform Inspection Procedure 6 "Poor Reception." Inspection Procedure 6
No sound only when the CD is played : Perform Inspection Procedure 8 "CD (compact disk)/DVD (Video Disk) cannot be Played." Inspection Procedure 8
No sound only when the DVD is played : Perform Inspection Procedure 8 "CD (compact disk)/DVD (Video Disk) cannot be Played." Inspection Procedure 8 or Inspection Procedure 9 "Image of a DVD (Video Disk) is Played, but no Sound is Played." Inspection Procedure 9
No sound only when the music server is used : Go to Step 8.
No sound from any of the sources : Go to Step 2.
STEP 2. Check the ETACS-ECU coding data.
Use scan tool MB991958 to diagnose the CAN bus lines.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III)." Scan Tool Connecting
2. Turn the ignition switch to "ON" position.
3. Operate the scan tool MB991958 to read the ETACS-ECU option coding information (Refer to general (Body and Chassis), Coding Table).
4. Check that the "Speaker" is set to "Premium."
Q: Is the check result normal?
YES : Go to Step 3.
NO : Operate scan tool MB991958 to set the option coding "Speaker" to "Premium," and check the trouble symptom.
STEP 3. Check the MMCS service mode, CAN communication confirmation, and coding data.
1. Display the CAN Communication Confirmation and Coding Data of the MMCS service mode. Service Mode
2. Check if PREMIUM is displayed.
Q: Is the check result normal?
YES : Go to step 4.
NO : Go to step 5.
STEP 4. Check the service data log for the MMCS service mode.
With the service data log of MMCS service mode displayed, check if the service data log for SP (speaker) is displayed. Service Mode
Q: Is the service data log for SP (speaker) displayed?
YES : Go to step 5.
NO : Go to step 8.
STEP 5. Using scan tool MB991958, diagnose the CAN bus line.
Use scan tool MB991958 to diagnose the CAN bus lines.
1. Turn the ignition switch to "ON" position.
2. Diagnose the CAN bus line.
Q: Is the check result normal?
YES : Go to Step 6.
NO : Repair the CAN bus line.
STEP 6. Using scan tool MB991958, read the CAN box unit diagnostic trouble code.
Check again if the DTC is set to the CAN box unit.
Q: Is the DTC set?
YES : Troubleshoot the MMCS. Diagnostic Trouble Code Descriptions
NO : Go to Step 7.
STEP 7. Using scan tool MB991958, read the ETACS-ECU diagnostic trouble code. Check if the diagnostic trouble code is set to the ETACS-ECU.
Q: Is the DTC set?
YES : Diagnose the ETACS-ECU (Refer to ETACS-ECU Troubleshooting). Diagnostic Trouble Code Descriptions
NO : Go to Step 8.
STEP 8. Check the service data log for the MMCS service mode.
1. Display the service data log for the MMCS service mode. Service Mode
2. Check if the service data log for drive and HDD is displayed.
Q: Is the service data log displayed?
YES (The service data log for drive is displayed.) : Perform Inspection Procedure 8 "CD (compact disk)/DVD (Video Disk) cannot be Played." Inspection Procedure 8 or Inspection Procedure 9 "Image of a DVD (Video Disk) is Played, but no Sound is Played." Go to Step 9. Inspection Procedure 9
YES (The service data log for HDD is displayed.) : Abnormalities relating to high or low temperature may be present. Check if the audio visual navigation unit can output the sound at the operable temperature. If it cannot output the sound, go to Step 9.
YES (The service data log for AMP is displayed.) : Go to Step 9.
NO : Go to Step 9.
STEP 9. Perform "Network/Connect Line Check" in the MMCS service mode.
1. Display "Network/Connect Line Check" in the MMCS service mode. Service Mode
2. Check if "DVD Drive OK" is displayed.
3. Check if "HDD Drive OK" is displayed.
4. Check if "Premium Audio OK" is displayed.
Q: Is the check result normal?
YES : Go to Step 18.
NO : Go to Step 10.
STEP 10. Check audio amplifier connector D-126 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is audio amplifier connector D-126 in good condition?
YES : Go to Step 11.
NO : Repair or replace the damaged component(s). Refer to general (electrical), Harness Connector Inspection.
STEP 11. Check the ground circuit to the rear monitor. Measure the resistance at audio amplifier connector D-126.
1. Disconnect audio amplifier connector D-126, and measure the resistance available at the wiring harness side of the connector.
2. Measure the resistance between terminal 24 and ground.
OK: The resistance should be 2 ohms or less
3. Measure the resistance between terminal 31 and ground.
OK: The resistance should be 2 ohms or less
4. Measure the resistance between terminal 32 and ground.
OK: The resistance should be 2 ohms or less
Q: Is the measured resistance 2 ohms or less?
YES : Go to Step 13.
NO : Go to Step 12.
STEP 12. Check the wiring harness between audio amplifier connector D-126 (terminal 24, 31, 32) and ground.
- Check the ground wires for open circuit.
Q: Is the wiring harness between audio amplifier connector D-126 (terminal 24, 31, 32) and ground in good condition?
YES : The trouble can be an intermittent malfunction (Refer to general (Body and Chassis), How to use Troubleshooting/inspection Service Points, How to Cope with Intermittent Malfunction).
NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 13. Check the power supply circuit to the ETACS-ECU. Measure the voltage at audio amplifier connector D-126.
1. Disconnect audio amplifier connector D-126, and measure the voltage available at the wiring harness-side connector.
2. Measure the voltage between terminal 25 and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
3. Measure the voltage between terminal 35 and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
4. Measure the voltage between terminal 36 and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery positive voltage)?
YES : Go to Step 15.
NO : Go to Step 14.
STEP 14. Check the wiring harness between audio amplifier connector D-126 (terminal 25, 35, 36) and fusible link (36).
NOTE: Also check intermediate connector C-129 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-129 is damaged, repair or replace the connector as described in general (electrical), Harness Connector Inspection.
- Check the power supply line for open circuit and short circuit.
Q: Is the wiring harness between audio amplifier connector D-126 (terminal 25, 35, 36) and fusible link (36) in good condition?
YES : Go to Step 15.
NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 15. Check audio visual navigation unit connector C-06, C-10 and audio amplifier connector D-127 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is audio visual navigation unit connector C-06 and audio amplifier connector D-127 in good condition?
YES : Go to Step 16.
NO : Repair or replace the damaged component(s). Refer to general (electrical), Harness Connector Inspection.
STEP 16. Check the wiring harness between audio visual navigation unit connector C-06 (terminal 82) and audio amplifier connector D-127 (terminal 3)
NOTE: Also check intermediate connectors C-15 and C-22 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-15 or C-22 is damaged, repair or replace the connector as described in general (electrical), Harness Connector Inspection.
- Check the communication lines for open circuit and short circuit.
Q: Is the wiring harness between audio visual navigation unit connector C-06 (terminal 82) and audio amplifier connector D-127 (terminal 3) in good condition?
YES : Go to Step 17.
NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 17. Check the wiring harness between audio visual navigation unit connector C-10 (terminal 6) and audio amplifier connector D-127 (terminal 34)
NOTE: Also check intermediate connectors C-15 and C-22 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-15 or C-22 is damaged, repair or replace the connector as described in general (electrical), Harness Connector Inspection.
- Check the communication lines for open circuit and short circuit.
Q: Is the wiring harness between audio visual navigation unit connector C-10 (terminal 6) and audio amplifier connector D-126 (terminal 34) in good condition?
YES : Go to Step 18.
NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 18. Retest the system
Check that the audio sound is output.
Q: Is the check result normal?
YES : The trouble can be an intermittent malfunction (Refer to general (Body and Chassis) How to use Troubleshooting/inspection Service Points How to Cope with Intermittent Malfunction).
NO : Go to step 19.
STEP 19. Retest the system
Temporarily replace the audio visual navigation unit and check if the sound is output.
Q: Is the check result normal?
YES : Replace the audio visual navigation unit.
NO : Replace the audio amplifier.