Inspection Procedure 2

INSPECTION PROCEDURE 2: The audio information is not displayed normally.







CIRCUIT OPERATION
The multi-center display unit receives information from the radio and CD player via M bus communication to display the audio system operation condition.

TECHNICAL DESCRIPTION (COMMENT)
The audio system operation screen will be frozen if the multi-center display have received abnormal data from the radio and CD player via M-bus communication within 30 seconds.

TROUBLESHOOTING HINTS
- Malfunction of multi-center display unit
- Malfunction of radio and CD player
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.


DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set

STEP 1. Check radio and CD player connector C-117 and multi-center display unit connector C-05 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is radio and CD player connector C-117 and multi-center display unit connector C-05 in good condition?

YES : Go to Step 2.

NO : Repair or replace the component(s).

STEP 2. Check the wiring harness between radio and CD player connector C-117 (terminal 22, 21 and 27) and multi-center display unit connector C-05 (terminal 9, 8 and 10).







- Check the wiring harness for open circuit and short circuit.

Q: Is the wiring harness between radio and CD player connector C-117 (terminal 22, 21 and 27) and multi-center display unit (middle grade type) connector C-05 (terminal 9, 8 and 10) in good condition?

YES : Go to Step 3.

NO : Repair the wiring harness.

STEP 3.Using the oscilloscope, check the M BUS line.

1. Connect the multi-center display unit connector C-05 and radio and CD player connector C-117.







2. Connect the oscilloscope probe to terminal 10 of the multi-center display unit connector by backprobing.
3. Turn the ignition switch to "ACC" position.
4. Operate each of the radio and CD player switches.

Q: Is a wave pattern displayed?

YES : Intermittent malfunction.

NO : Replace multi-center display unit and then go to Step 4.

STEP 4. Retest the system

Confirm that the audio operation screen is displayed normally.

Q: Is the check result satisfactory?

YES : The procedure is complete.

NO : Replace radio and CD player and then go to step 5.

STEP 5. Retest the system

Confirm that the audio operation screen is displayed normally.

Q: Is the check result satisfactory?

YES : The procedure is complete.

NO : Go to step 1.