No.4 RBC UNIT GENERATES ABNORMAL NOISE OR VIBRATION

id030300801000

Possible Cause

• The 4WD lock system is designed to improve driveability on snow covered roads and to free a stuck vehicle. Abnormal noise or vibration may occur while turning on a dry surface with the 4WD lock on.

• RBC unit generates an abnormal noise or vibration while driving

• Propeller shaft malfunction or improper installation

• Engine mount, differential mount malfunction

• If the malfunction occurs at a certain vehicle speed or engine speed, resonance caused by the rotating parts of the vehicle, such as engine, propeller shaft, rear differential, and tires, may be the cause.

• Resonance caused by engine vibration (mainly exhaust system)

• Resonance caused by rear differential

• RBC unit malfunction

Diagnostic Procedure

STEP

INSPECTION

ACTION

1
INSPECT PARTS FOR IMPROPER INSTALLATION
• Inspect the following parts for improper installation.
- Propeller shaft (including bending and joint parts operation)
- Center bearing
- Engine mount
- Differential mount
- Hub bearing
- Exhaust system parts
- ABS wheel-speed sensor rotor
• Is the malfunction verified?
Yes
Repair or replace any malfunction.
No
Go to the next step.
2
INSPECT FOR REAR DIFFERENTIAL MALFUNCTION
• Install a different brand of tires.
Caution
• When a different brand of tires are installed, the same malfunction may occur under different conditions (engine and vehicle speed). Do not confuse this with the malfunction which the customer indicated.
• Drive the vehicle under the same conditions (engine speed, gear position, vehicle speed, and accelerator opening angle) which the customer indicated.
• Is the level of the malfunction reduced?
Yes
The 4WD system is normal. (Resonance caused by the vehicle rotating parts)
No
Install the original tires and go to the next step.
3
INSPECT REAR DIFFERENTIAL
• Inspect the rear differential for the following.
- Backlash
- Tooth meshing
(See REAR DIFFERENTIAL DISASSEMBLY/ASSEMBLY.)
• Are the results normal?
Yes
Replace the RBC unit.
No
Inspect and adjust any malfunction.