| Diagnosis Chart Correction Codes |
|
| ADB-Accessory Drive Belts. Excessive wear or looseness may cause droning noise or flutter. |
| AN-Rear Axle Noise. May be caused by gears or bearings. |
| DEM-Damaged Engine Mounts. May allow engine or accessories to contact body. |
| EA-Engine Accessories. Loose or broken accessories: power steering pump, air conditioning compressor, alternator, water pump, etc. |
| PSY-Propeller Shaft and Yokes. Undercoating, runout, and balance not a cause for vibration below 45 mph. Possible cause of audible vibration only between 55 and 75 mph. |
| TB-Tire Balance. Not a cause of vibration below 30 mph. Dynamic unbalance not a cause below 40 mph. Check balance of wheels and tires. |
| TEB -Transmission Extension Housing Bushing. Looseness usually
accompanied by oil seal leakage. |
|
| MECHANICAL VIBRATION DIAGNOSIS |
| Vibration Category |
Correction Code for Vibrations Within Specific
MPH Ranges |
| |
10 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
| Car Speed Sensitive |
|
|
|
UJ and TEB |
WB |
TRR |
TB PSY |
TLR |
|
| Torque Sensitive |
UJA |
|
|
UJ and TEB |
|
|
|
UJA |
|
| Engine Speed Sensitive |
|
EA DEM |
|
|
|
|
|
|
|
| AUDIBLE VIBRATION DIAGNOSIS |
| Vibration Category |
Correction Code for Vibrations Within Specific mph Ranges |
|
10 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
| Car Speed Sensitive |
|
|
|
UJA
UJ and TEB |
WB |
TW |
PSY |
|
|
| Torque Sensitive |
|
|
|
|
AN
UJ and TEB |
|
|
|
|
| Engine Speed Sensitive |
|
DEM |
ADB |
|
|
|
|
|
|
|
| Diagnosis Chart Correction Codes |
|
| TLR-Tire and Wheel Lateral Runout. Not usually a cause of vibration below 60 mph. |
| TRR-Tire and Wheel Radial Runout. Not a cause of vibration below 20 mph. The speed required to cause vibration increases as runout decreases. |
| TW-TireWear. Uneven wear patterns (cupped) may generate a singing whine at higher speeds and degenerate to a growl at lower speeds and may be accompanied by vibration similar to that caused by wheel bearings. |
| UJ-Universal Joints. Universal joints can cause vibrations at any speed. |
| UJA-Universal Joint Angles. Incorrect angles may cause mechanical vibration below 15 mph and mechanical or audible vibration between 30 and 55 mph. |
| WB-Wheel Bearings. If rough or damaged, will cause a growling or grinding noise at low speeds, or a whining noise at high speeds. Loose wheel bearings can cause mechanical vibrations at 50 to 60 mph. |
|