A Diagnostic Starting Point - Rear Drive Axle
Begin the system diagnosis by reviewing the Rear Axle Disassembled Views and Rear Axle Description and Wheel Drive Shaft Description and Operation in Wheel Drive Shafts. Reviewing the description and operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description and operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Rear Drive Axle in order to identify the correct procedure for diagnosing the system and where the procedure is located.
Symptoms - Rear Drive Axle
Strategy Based Diagnostics
Review the system operations in order to familiarize yourself with the system functions. Refer to Rear Axle Disassembled Views and Rear Axle Description and Wheel Drive Shaft Description and Operation in Wheel Drive Shafts. All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system problem. The diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy Based Diagnosis in General Information.
Visual/Physical Inspection
| • | Inspect for aftermarket devices, which could affect the operation of the vehicle. Refer to Checking Aftermarket Accessories in Wiring Systems. |
| • | Inspect the easily accessible or visible system components for obvious damage or conditions, which could cause the symptom. |
| • | Check for the correct lubricant level and the proper viscosity. |
| • | Verify the exact operating conditions under which the concern exists. Note factors such as vehicle speed, road conditions, ambient temperature, and other specifics. |
| • | Compare the driving characteristics or sounds (if applicable) to a known good vehicle and make sure you are not trying to correct a normal condition. |
Intermittent
Test the vehicle under the same conditions that the customer reported in order to verify the system is operating properly.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
| • | A Diagnostic Starting Point - Vibration Diagnosis and Correction in Vibration Diagnosis and Correction |
| • | A Diagnostic Starting Point - Automatic Transmission in Automatic Transmission - 4L60-E |
| • | Transmission Noisy in Manual Transmission - MM6 |
| • | Driveline Noise Diagnosis in Propeller Shaft |
| • | Clutch Noisy in Clutch |
| • | Noisy in Drive |
| • | Noisy When Coasting |
| • | Intermittent Noise |
| • | Constant Noise |
| • | Noisy on Turns |
| • | Rear Axle Lubricant Leak Diagnosis |
Noisy in Drive
Cause | Correction |
|---|---|
Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Lubricant Level Check . | |
Worn clutch disc and/or pressure plate assembly | Repair or replace as required. Refer to Clutch Noisy in Clutch. |
Transmission noise | Repair or replace as required. Refer to Transmission Noisy in Manual Transmission - MM6 or A Diagnostic Starting Point - Automatic Transmission in Automatic Transmission - 4L60-E. |
Driveline assembly noise | Repair or replace as required. Refer to Driveline Noise Diagnosis in Propeller Shaft. |
Worn axle shaft constant velocity joints | Replace the constant velocity joints as required. |
Worn, loose, or damaged axle mount and/or bracket | Repair or replace the axle mount and/or bracket as required. |
Bearing noise within the differential assembly | A grinding or roar type noise will increase or decrease relative to the vehicle speed.
|
Gear set whine noise within the differential assembly | A whine type noise will increase or decrease relative to the vehicle speed (approximately 50-60 mph). Typical causes of a gear set whine type noise may include incorrect backlash and/or pinion depth adjustment or worn or scored gear set teeth.
|
Noisy When Coasting
Cause | Correction |
|---|---|
Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Lubricant Level Check . | |
Worn axle shaft constant velocity joints | Replace the constant velocity joints as required. |
Worn, loose, or damaged axle mount and/or bracket | Repair or replace the axle mount and/or bracket as required. |
Bearing noise within the differential assembly | A grinding or roar type noise will increase or decrease relative to the vehicle speed.
|
Gear set whine noise within the differential assembly | A whine type noise will increase or decrease relative to the vehicle speed (approximately 50-60 mph). Typical causes of a gear set whine type noise may include incorrect backlash and/or pinion depth adjustment or worn or scored gear set teeth.
|
Intermittent Noise
Cause | Correction |
|---|---|
Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Lubricant Level Check . | |
Worn, loose, or damaged axle mount and/or bracket | Repair or replace the axle mount and/or bracket as required. |
Incorrect gear oil | Replace with the correct gear oil and friction modifier additive. Refer to Sealers, Adhesives, and Lubricants . |
Constant Noise
Cause | Correction |
|---|---|
Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Lubricant Level Check . | |
Low gear oil levels | Faulty oil seals or other type leaks may contribute to lower than required fluid levels. Refer to Rear Axle Lubricant Leak Diagnosis. Fill to the proper level with the correct gear oil and friction modifier additive. Refer to Sealers, Adhesives, and Lubricants and Lubricant Change . |
Worn, loose, or damaged axle mount and/or bracket | Repair or replace the axle mount and/or bracket as required. |
Bearing noise within the differential assembly | A grinding or roar type noise will increase or decrease relative to the vehicle speed.
|
Gear set whine noise within the differential assembly | A whine type noise will increase or decrease relative to the vehicle speed (approximately 50-60 mph). Typical causes of a gear set whine type noise may include incorrect backlash and/or pinion depth adjustment or worn or scored gear set teeth.
|
Noisy on Turns
Cause | Correction |
|---|---|
Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Lubricant Level Check . Operate the vehicle turning in tight circles in both left and right directions. A chatter type concern may indicate an incorrect type gear oil, lack of the friction modifier additive, or worn friction discs and/or plates. | |
Worn or loose rear axle mount and/or bracket | Repair or replace as required. |
Worn axle shaft constant velocity joints | Replace the constant velocity joints as required. |
Worn wheel bearings | Replace the wheel bearings as required. |
Incorrect gear oil | Fill to the proper level with the correct gear oil and friction modifier additive. Refer to Sealers, Adhesives, and Lubricants and Lubricant Change . |
Worn clutch plates | Replace the friction discs and plates as required. |
Rear Axle Lubricant Leak Diagnosis
Cause | Correction |
|---|---|
Upon completion of all repairs, refill the axle with the proper amounts of axle lubricant and friction modifier additive. Refer to Lubricant Change and Lubrication Specifications . | |
Restricted or damaged vent valve assembly | Repair or replace the vent valve as required. |
Worn, scored, or missing drain and/or fill plug sealing washers | Install new sealing washers and tighten the plugs per specifications. |
Damaged speed sensor and/or O-ring seal | Replace the speed sensor and/or the O-ring seal as required. |
Leaking transmission mounting stud | Remove the mounting stud, and reseal the threads. |
Rear cover O-ring seal | Replace the rear cover O-ring seal. |
Left or right side cover O-ring seal | Replace the side cover O-ring seal as required. |
Worn or damaged axle shaft oil seals | Replace the axle shaft oil seals as required. |
Worn or damaged carrier seal plate O-ring or oil seal (automatic transmission only) | Replace the O-ring and oil seal as required. |
Housing or side cover porosity | Replace the housing and/or the covers as required. |
