Inspection Procedure 1
Inspection Procedure 1: Power of the radio and CD player does not turn ON when the Ignition switch is in the "ACC"
position or "ON" Position.
CAUTION:
Before replacing the radio and CD player, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
CAUTION:
When the ignition switch is turned to the ACC position for 30 minutes with the ETACS-ECU function, the ACC power is cut-off automatically. For this function, the time to cut-off can be changed with the operation of ETACS system by the scan tool MB991958. (Refer to Programming and Relearning.)
OPERATION
When the ignition switch is in the ON or ACC position, the radio and CD player power can be turned ON. With the radio and CD player power ON, when the ignition switch is turned to the OFF position, the power for radio and CD player is also turned OFF.
TECHNICAL DESCRIPTION (COMMENT)
Provided that the audio diagnostic trouble code is not set, if the power for radio and CD player cannot be turned ON, the radio and CD player, or power supply circuit for radio and CD player may have a problem, or the option coding information may be inconsistent.
TROUBLESHOOTING HINTS
- Radio and CD player may be defective
- The ETACS-ECU may be defective
- Option coding information inconsistency
- 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
- 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. ETACS-ECU coding data check.
(1)Operate scan tool MB991958 to read the ETACS-ECU option coding information Coding List).
(2)Check that the "AUDIO" is set to "Present."
Q. Is the check result normal?
YES Go to Step 2.
NO Operate scan tool MB991958 to set the option coding "AUDIO" to "Present," and check the trouble symptom.
STEP 2. Using scan tool MB991958, diagnose the CAN bus line.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1)
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.
Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to "ON" position.
(3)Diagnose the CAN bus line.
Q. Is the check result normal?
YES Go to Step 3.
NO Repair the CAN bus line. CAN Bus Diagnostics Chart.) On completion, go to Step 3.
STEP 3. 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 Troubleshoot the ETACS-ECU Electronic Time and Alarm Control System (ETACS)), and then go to Step 4.
NO Go to Step 4.
STEP 4. Using scan tool MB991958, check data list.
Check the input signal of ACC relay.
- Turn the ignition switch to the ACC position.
OK: Normal condition is displayed.
Q. Is the check result normal?
YES Go to Step 5.
NO Inspection Procedure 1.
STEP 5. Check ETACS-ECU connector C-311 and radio and CD player connector C-104 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q. Are ETACS-ECU connector C-311 and radio and CD player connector C-104 in good condition?
YES Go to Step 6.
NO Repair or replace the damaged component(s) Harness Connector Inspection).
STEP 6. Check the power supply circuit to the radio and CD player.
Measure the voltage at radio and CD player connector C-104.
(1)Disconnect the connector, and measure at the wiring harness-side connector.
(2)Measure the voltage between terminal 30 and ground.
OK: Battery positive voltage
Q. Is the measured voltage battery positive voltage?
YES Go to Step 8.
NO Go to Step7.
STEP 7. Check the wiring harness between ETACS-ECU connector C-311
(terminal 7) and radio and CD player connector C-104 (terminal 30).
- Check the power supply lines (battery power supply) for open circuit and short circuit.
NOTE:
Also check intermediate connector C-39, C-128 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-39, C-128 is damaged, repair or replace the connector as described in Harness Connector Inspection Harness Connector Inspection.
Q. Is the wiring harness between ETACS-ECU connector C-311 (terminal 7) and radio and CD player connector C-104 (terminal 30) in good condition?
YES Go to Step 8.
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 8. Check the power supply circuit to the ETACS-ECU. Measure the voltage at ETACS-ECU connector C-307.
(1)Disconnect the connector, and measure at the wiring harness-side connector.
(2)Measure the voltage between terminal 2 and ground.
OK: Battery positive voltage
Q. Is the measured voltage battery positive voltage?
YES Go to Step 10.
NO Go to Step 9.
STEP 9. Check the wiring harness between ETACS-ECU connector C-307
(terminal 2) and fusible link (36)
- Check the power supply line for open circuit and short circuit.
Q. Is the wiring harness between ETACS-ECU connector C-307 (terminal 2) and fusible link
(36) in good condition?
YES Go to Step 10.
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 10. Check that the radio and CD player is correctly grounded
The radio and CD player should be connected to the ground with an assembling screw.
Q. Is the radio and CD player correctly grounded?
YES Go to Step 11.
NO Securely install and ground the radio and CD player.
STEP 11. Retest the system
Check if the radio and CD player power is turned ON.
Q. Is the check result normal?
YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the radio and CD player.