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.

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.
1		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)
2		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.
3		No	Inspect and adjust any malfunction.