B2421

DTC B2421: Radio tuner

CAUTION:
- If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
- Before replacing the radio and CD player or CD changer, be sure to check that the power supply circuit, ground circuit, and communication circuit are normal.

TROUBLE JUDGEMENT
If the communication cannot be established consecutively for 10 times between the incorporated tuner of radio and CD player or CD changer and the micro- computer, the diagnostic trouble code is set.

COMMENTS ON TROUBLE SYMPTOM
The radio and CD player or CD changer or CAN bus line may have a problem.

PROBABLE CAUSES
- Malfunctions of radio and CD player or CD changer
- Malfunction of CAN bus line wiring harness and connector

DIAGNOSIS

Required Special Tools:
- 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. Using scan tool MB991958, diagnose the CAN bus line.

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 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 2.

NO : Repair the CAN bus line. (Refer to Controller area network Diagnosis) On completion, go to Step 2.

STEP 2. Recheck for diagnostic trouble code.

Check again if the DTC is set to the radio and CD player or CD changer.

1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if the DTC is set.

Q: Is the DTC set?

YES : Replace the radio and CD player or CD changer.

NO : 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).