Inspection Procedure 4
INSPECTION PROCEDURE 4: On the Audio Screen, "E" cannot Proceed to Next Screen.M-BUS Line Circuit:
CIRCUIT OPERATION
The multi-center display unit receives information from the radio and CD player with CD changer [Vehicles with audio amplifier] or radio and CD player [Vehicles without audio amplifier] 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 with CD changer [Vehicles with audio amplifier] or radio and CD player [Vehicles without audio amplifier] via M-bus communication within 30 seconds. If the abnormal data is received further 30 seconds from that point, a message "E" will be displayed.
TROUBLESHOOTING HINTS
- Malfunction of multi-center display unit
- Malfunction of radio and CD player with CD changer [Vehicles with audio amplifier] or radio and CD player [Vehicles without audio amplifier]
- 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
- MB992006: Extra Fine Probe
STEP 1. Check of the display.
Q: Is "E" displayed?
YES : Go to Step 2.
NO : Go to Step 4.
STEP 2. Check radio and CD player with CD changer connector C-119 [Vehicles with audio amplifier] or radio and CD player connector C-118 [Vehicles without audio amplifier] and multi-center display unit connector C-06 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is radio and CD player with CD changer connector C-119 [Vehicles with audio amplifier] or radio and CD player connector C-118 [Vehicles without audio amplifier] and multi-center display unit connector C-06 in good condition?
YES : Go to Step 3.
NO : Repair or replace the component(s). Then go to step 1.
STEP 3. Check the wiring harness between radio and CD player with CD changer connector C-119 (terminal 27, 28, 38 and 39) [Vehicles with audio amplifier] or radio and CD player connector C-118 (terminal 21, 22, 26 and 27) [Vehicles without audio amplifier] and multi-center display unit connector C-06 (terminal 8, 9, 7 and 10).
Q: Is the wiring harness between radio and CD player with CD changer connector C-119 (terminal 27, 28, 38 and 39) [Vehicles with audio amplifier] or radio and CD player connector C-118 (terminal 21, 22, 26 and 27) [Vehicles without audio amplifier] and multi-center display unit connector C-06 (terminal 8, 9, 7 and 10) in good condition?
YES : Go to Step 4.
NO : Repair the wiring harness and then go to step 1.
STEP 4.Using the oscilloscope, check the M-BUS line.
1. Connect the multi-center display unit connector C-06 and radio and CD player with CD changer connector C-119 [Vehicles with audio amplifier] or radio and CD player connector C-118 [Vehicles without audio amplifier].
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 with CD changer switches [Vehicles with audio amplifier] or radio and CD player switches[Vehicles without audio amplifier].
Q: Is a wave pattern displayed?
YES : Go to Step 5.
NO : Replace multi-center display unit and then go to Step 6.
STEP 5. Retest the system
Confirm that the audio operation screen is displayed normally.
Q: Is the check result satisfactory?
YES : Intermittent malfunction.
NO : Replace radio and CD player with CD changer [Vehicles with audio amplifier] or radio and CD player [Vehicles without audio amplifier] and then go to step 6.
STEP 6. 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.