Symptom Chart
The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).
Symptom Chart: Differential
Symptom Chart - Differential
| Condition | Action |
| Axle Overheating |
GO to Pinpoint Test A |
| No Torque at Rear Wheels |
GO to Pinpoint Test B |
| Check the message center for an All Wheel Drive system fault message. |
GO to Pinpoint Test B |
| Yellow, green or milky axle lubricant in low-mileage vehicles |
GO to Pinpoint Test C |
| Lubricant leakage from pinion seal, axle shaft seal, housing joint, RDU clutch motor or speed sensor |
GO to Pinpoint Test D |
Symptom Chart: NVH
Symptom Chart
| Condition | Action |
| Howl or whine of axle - rear axle |
GO to Pinpoint Test E |
| Transmission clunk - loud clunk when shifting from REVERSE to DRIVE. |
GO to Pinpoint Test F |
| Transmission shudder - occurs when the vehicle begins to move forward from a stop. |
GO to Pinpoint Test G |
| Chatter, clunk or creak - rear axle noise when turning the vehicle |
GO to Pinpoint Test H |
| Grunt - usually associated with driveline shuck experienced during acceleration from a complete stop. |
GO to Pinpoint Test I |
| Noise isolated to RDU using normal NVH diagnostics |
GO to Pinpoint Test J |
| Driveline shudder - occurs during low speed acceleration or stopping. |
GO to Pinpoint Test K |
Global Customer Symptom Codes (GCSC) Table
The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).
| Symptom | Action |
| Key On Engine Running/Drive/Move > Run > Overheat > Continuous |
GO to Pinpoint Test A |
| Starting/Operating/Moving > Towing > 4 x 4 Function > Does Not Work |
GO to Pinpoint Test B |
| Start/Perform/Move > Fluids > Axle > Consumption |
GO to Pinpoint Test A |
| Start/Perform/Move > Fluids > Axle > Visible Leak |
GO to Pinpoint Test A |
| Start/Perform/Move > Fluids > Axle > Visible Leak |
GO to Pinpoint Test D |
| Start/Perform/Move > Fluids > Axle > Visible Leak |
GO to Pinpoint Test E |
| Start/Perform/Move > Fluids > Axle > Contamination |
GO to Pinpoint Test A |
| Start/Perform/Move > Fluids > Axle > Contamination |
GO to Pinpoint Test C |
| Park/Neutral/Reverse > Noise > Drive/Motion > Always |
GO to Pinpoint Test E |
| Park/Neutral/Reverse > Noise > Drive/Motion > Always |
GO to Pinpoint Test F |
| Park/Neutral/Reverse > Noise > Drive/Motion > Always |
GO to Pinpoint Test G |
| Park/Neutral/Reverse > Noise > Drive/Motion > Always |
GO to Pinpoint Test H |
| Park/Neutral/Reverse > Noise > Drive/Motion > Always |
GO to Pinpoint Test J |
| Park/Neutral/Reverse > Vibration > Drive/Motion > Intermittent |
GO to Pinpoint Test I |
| Park/Neutral/Reverse > Vibration > Drive/Motion > Intermittent |
GO to Pinpoint Test K |
Pinpoint Tests
DIAGNOSTIC TEST A: AXLE OVERHEATING
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Low axle lubricant level
- Incorrect or contaminated lubricant type
- Worn or damaged internal gear
|
| A1 CHECK THE AXLE LUBRICANT LEVEL |
- Check the lubricant level.
Is the lubricant level low?
| Yes |
REFER TO: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures). |
|
| A2 CHECK THE AXLE CONDITION |
- Inspect the axle for damage.
- Check the axle lubricant.
Was any damage found?
| Yes |
Repair as necessary. If necessary, clean and fill the axle to specification.
REFER TO: Specifications (205-02 Rear Drive Axle/Differential, Specifications). If necessary, install a new axle assembly.
REFER TO: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
| No |
Inspect the vehicle for other axle-related symptoms. |
|
DIAGNOSTIC TEST B: NO TORQUE AT REAR WHEELS
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- All Wheel Drive System Fault
|
| B1 CHECK THE ALL WHEEL DRIVE (AWD) SYSTEM FAULT MESSAGE IN THE MESSAGE CENTER |
- Check the message center for an All Wheel Drive system fault message.
Is there an All Wheel Drive system fault message in the message center?
| No |
Inspect the vehicle for other axle-related symptoms. |
|
| B2 CHECK THE ALL WHEEL DRIVE (AWD) SYSTEM OPERATION |
- Check the All Wheel Drive system operation.
Does the All Wheel Drive system operate?
| Yes |
Inspect the vehicle for other axle-related symptoms. |
|
DIAGNOSTIC TEST C: YELLOW, GREEN OR MILKY AXLE LUBRICANT IN LOW-MILEAGE VEHICLE
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Damaged axle housing
- Damaged axle vent
|
| C1 CHECK THE AXLE HOUSING AND VENT |
- Inspect the axle housing and vent for damage or leakage.
Is any damage or leakage found?
| No |
Refer to Axle Fluid Analysis in this section. |
|
PINPOINT TEST D: LUBRICANT LEAKAGE FROM PINION SEAL, AXLE SHAFT SEAL OR CONTROL ARM INTO HOUSING
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- vent
- Damage to the seal contact area or dust deflector on the pinion flange dust shield
|
| D1 CHECK THE AXLE VENT FOR BLOCKAGE |
- Inspect the axle housing vent for blockage.
Is a blockage found?
| Yes |
Clean the axle housing vent. |
|
| D2 CHECK THE PINION SEAL, AXLE SHAFT SEALS AND DUST DEFLECTOR |
- Inspect the seal contact area or dust deflector for damage.
Was any damage found?
| Yes |
Install a new pinion flange and pinion seal.
REFER TO: Pinion Flange (205-02 Rear Drive Axle/Differential, Removal and Installation).
REFER TO: Pinion Seal (205-02 Rear Drive Axle/Differential, Removal and Installation). Install a new axle shaft seal and/or pinion seal if damage is found.
REFER TO: Rear Axle Shaft Seal (205-02 Rear Drive Axle/Differential, Removal and Installation). If the housing or RDU clutch motor leakage is found, replace the RDU.
REFER TO: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). If leakage is found from the RDU speed sensor, install a new speed sensor.
REFER TO: Rear Drive Unit (RDU) Speed Sensor (205-02 Rear Drive Axle/Differential, Removal and Installation). |
| No |
The system is currently operating correctly. |
|
PINPOINT TEST E: HOWL OR WHINE OF AXLES
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Low axle lubricant level
- Damaged axle housing
- Worn or damaged differential and gear assembly
|
| E1 CHECK THE LUBRICANT LEVEL |
- Check the lubricant level.
Is the lubricant level low?
| Yes |
Fill the axle to specification.
REFER TO: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures). |
|
| E2 CHECK THE AXLE HOUSING FOR DAMAGE |
- Inspect the axle housing for damage.
- Inspect the rear differential subframe bushings.
Was any damage found?
| Yes |
If necessary, install a new axle assembly.
REFER TO: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). Install a new rear subframe as necessary.
REFER TO: Rear Subframe (502-00 Uni-Body, Subframe and Mounting System, Removal and Installation). |
| No |
Inspect the vehicle for other axle-related symptoms. |
|
PINPOINT TEST F: TRANSMISSION CLUNK - HARSH CLUNK WHEN SHIFTING FROM REVERSE TO DRIVE
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Axle lubricant level
- Excessive axle play
|
| F1 CHECK THE LUBRICANT LEVEL |
- Check the lubricant level.
Is the lubricant level low?
| Yes |
Fill the axle to specification.
REFER TO: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures). |
| No |
Inspect the vehicle for other axle-related symptoms. |
|
PINPOINT TEST G: TRANSMISSION CLUNK - OCCURS WHEN VEHICLE BEGINS TO MOVE FORWARD FROM A STOP
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
|
| G1 CHECK FOR LOOSE BOLTS |
Are any bolts loose?
| Yes |
Tighten to specification.
REFER TO: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
| No |
Inspect the vehicle for other axle-related symptoms. |
|
PINPOINT TEST H: CHATTER, CLUNK OR CREAK - REAR AXLE NOISE WHEN TURNING THE VEHICLE
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Incorrect or contaminated lubricant
- Worn or damaged differential (differential side gears and pinions)
- Damaged RDU clutch - plates fused from both wheels or rear differential bias extended forward
- Damaged axle shaft or axle shaft retaining ring.
|
| H1 CHECK THE AXLE CONDITION |
- Check the axle lubricant.
Was any damage found?
| Yes |
If necessary, drain and refill the rear axle lubricant to the specified level.
Refer to: Draining and Refilling the Differential (205-02 Rear Drive Axle/Differential, General Procedures). |
|
| H2 CHECK THE HALFSHAFT OR RETAINING RING |
- Inspect the axle shaft or the axle shaft retaining ring.
Was any damage found?
| Yes |
If necessary, install the halfshaft or halfshaft retaining ring.
Refer to: Rear Halfshaft (205-05 Rear Axle Shafts, Removal and Installation). |
|
| H3 CHECK THE DIFFERENTIAL |
- Inspect the differential and differential components.
Was any damage found?
| Yes |
If necessary, install a new axle assembly.
Refer to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
| No |
Inspect the vehicle for other axle-related symptoms. |
|
PINPOINT TEST I: CHATTER, TYPICALLY ASSOCIATED WITH HOLD WHEN ACCELERATING FROM A COMPLETE STOP
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Rear axle mounting bolts loose
- Loose suspension mounts
|
| I1 CHECK FOR LOOSE BOLTS |
Are any bolts loose?
| Yes |
Tighten to specification.
REFER TO: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
| No |
The system is currently operating correctly. |
|
PINPOINT TEST J: NOISE ISOLATED TO RDU (REAR DRIVE UNIT) USING NORMAL NVH (NOISE, VIBRATION AND HARSHNESS) DIAGNOSTICS
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
|
| J1 CHECK THE AXLE CONDITION |
- Check the axle lubricant.
Was any damage found?
| Yes |
If necessary, drain and refill the rear axle lubricant to the specified level.
Refer to: Draining and Refilling the Differential (205-02 Rear Drive Axle/Differential, General Procedures). |
|
| J2 CHECK THE DIFFERENTIAL |
- Inspect the differential and differential components.
Was any damage found?
| Yes |
If necessary, install a new axle assembly.
Refer to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
| No |
Inspect the vehicle for other axle-related symptoms. |
|
PINPOINT TEST K: TRANSMISSION HOLD - OCCURS DURING LOW-SPEED ACCELERATION OR STOPPING
Normal Operation and Fault Symptoms
REFER TO: Rear Drive Axle and Differential - Overview (205-02 Rear Drive Axle/Differential, Description and Operation).
Possible Sources
- Axle offset
- Loose axle bolts
- Driveline angle
|
| K1 CHECK THE AXLE MOUNTS AND REAR SUSPENSION FOR DAMAGE OR WEAR |
- Inspect the axle mounts and rear suspension for damage or wear.
Was wear or damage found?
| Yes |
Repair as necessary.
Refer to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
|
| K2 CHECK THE REAR AXLE FOR LOOSE BOLTS |
- Check the rear axle for loose bolts.
Are any bolts loose?
| Yes |
Tighten the bolts as necessary.
Refer to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). |
|
| K3 CHECK THE DRIVELINE ANGLES |
- Check the driveline angles for correctness.
Are the driveline angles correct?
| Yes |
Inspect the vehicle for other axle-related symptoms. |
|
Axle Fluid Analysis
A milky, yellow or green axle fluid appearance at the beginning of axle operation is the result of the yellow marking compound used at the assembly plant to check the gear tooth contact pattern. The marking compound in the fluid will gradually darken over time. The milky appearance will diminish and is not harmful and does not require fluid replacement.
Leak Analysis
Clean the leak area sufficiently to determine the exact source.
A clogged RDU housing vent can cause excessive wear of the pinion seal lip due to increased internal pressure.
Make sure the RDU lubricant level is at least 3-5 mm (1/8-3/16 in) below the bottom of the fill hole.
Axle Vent
A clogged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak has occurred, inspect the vent fitting or hose assembly. If the vent cannot be cleaned, install a new vent.
Pinion Seal
Pinion seal leaks are caused by the following conditions:
- Damaged seal
- Worn seal journal surface
If any of these conditions exist, install a new pinion seal.
- The pinion seal may be torn, cut or gouged if not installed correctly. The pinion seal spring may be dislodged from the pinion flange, allowing fluid to pass the lip.
- Metal shavings lodged at the seal lip may cause a fluid leak. This may wear a groove in the pinion flange and lead to pinion seal wear.
- If a seal leak occurs, install a new pinion seal and inspect the vent to make sure it is clean and free of foreign material.
If necessary, replace the pinion seal.
Refer to: Pinion Seal (205-02 Rear Drive Axle/Differential, Removal and Installation).
Pinion Nut
On some high-mileage vehicles, fluid may leak past the pinion nut threads. INSTALL a new pinion nut if necessary.
Refer to: Pinion Flange (205-02 Rear Drive Axle/Differential, Removal and Installation).
Differential Seals
NOTICE: When installing the axle shafts, do not allow the splines to contact the seals during installation, otherwise seal damage may occur.
Axle shaft seals are subject to the same types of damage as pinion seals if installed incorrectly. The seal bore must be clean and the edge free of burrs to avoid cutting or tearing the seal. The seal journal surface must be free of nicks, grooves and rough surface texture.
For differential seal information, refer to: Rear Axle Shaft Seal (205-02 Rear Drive Axle/Differential, Removal and Installation).