Inspection Procedure 2

Inspection Procedure 2: No Sound is Heard.

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 ETACS-ECU coding data.

1. Operate the scan tool MB991958 to read the ETACS-ECU option coding information (Refer to general (Body and Chassis) Coding Table).
2. Check that the "Speaker" is set to "Premium."

Q: Is the check result normal?

YES : Go to Step 2.

NO : Operate scan tool MB991958 to set the option coding "Speaker" to "Premium," and check the trouble symptom.

STEP 2. Check audio amplifier connector D-25 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is audio amplifier connector D-25 in good condition?

YES : Go to Step 3.

NO : Repair or replace the damaged component(s). Refer to general (electrical), Harness Connector Inspection.

STEP 3. Check the power supply circuit to the ETACS-ECU. Measure the voltage at audio amplifier connector D-25.

1. Disconnect audio amplifier connector D-25, 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 5.

NO : Go to Step 4.

STEP 4. Check the wiring harness between audio amplifier connector D-25 (terminal 25, 35, 36) and fusible link (36).

NOTE: Also check intermediate connector C-39 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-39 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-25 (terminal 25, 35, 36) and fusible link (36) in good condition?

YES : Go to Step 7.

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 5. Check audio visual navigation unit connector C-11 and audio amplifier connector D-26 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is audio visual navigation unit connector C-11 and audio amplifier connector D-26 in good condition?

YES : Go to Step 6.

NO : Repair or replace the damaged component (Refer to general (electrical) Harness Connector Inspection).

STEP 6. Check the wiring harness between audio visual navigation unit connector C-11 (terminal 82) and audio amplifier connector D-26 (terminal 3)

NOTE: Also check intermediate connectors C-22 and C-107 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-22 or C-107 is damaged, repair or replace the connector as described in general (electrical) Harness Connector Inspection.

- Check the communication lines for open circuit.

Q: Is the wiring harness between audio visual navigation unit connector C-11 (terminal 82) and audio amplifier connector D-26 (terminal 3) in good condition?

YES : Go to Step 7.

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 7. Retest the system

Replace the audio amplifier, then 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 : Replace the audio visual navigation unit.