Ford F150 Pickup. Instruction - part 645

F150 PICKUP . 

Total Backlash Check 

1. Raise and support the vehicle.  

2. Remove the driveshaft. Refer to DRIVESHAFT & UNIVERSAL JOINTS - F150 PICKUP .  

3. Install the special tool. 

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Clamp a rigid bar or pipe to the tool. Clamp the other end of the bar or pipe to the frame or a body 
member in order to prevent movement of the pinion flange. 

Fig. 21: Installing Pinion Flange Holding Tool 
Courtesy of FORD MOTOR CO. 

4. Lower the vehicle so that one rear wheel is resting on a wheel chock to prevent it from turning. The other 

rear wheel will be used to measure total rear axle backlash.  

5. Rotate the free wheel slowly, by hand, until the feeling of driving the rear axle is encountered. Place a 

mark on the side of the tire, 305 mm (12 inches) from the center of the wheel, with a crayon or chalk.  

6. While holding the crayon or chalk against the tire, rotate the wheel slowly in the opposite direction until 

the feeling of driving the rear axle is encountered again.  

7. Measure the length of the crayon or chalk mark on the tire. 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup

  

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If the length of the mark is 25.4 mm (1 inch) or less, the rear axle backlash is within allowable limits.  

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If the chalk mark is greater than 25.4 mm (1 inch), check for these conditions:  

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Elongation of the differential pinion shaft and holes in the differential case (4204).  

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Missing differential pinion thrust washer (4230) or differential side gear thrust washer (4228).  

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Galling of the differential pinion shaft (4211) and bore.  

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Excessive ring gear and pinion backlash. Follow the procedure for the type of rear axle to check backlash. 

Axle Shaft Bearing Noise 

Axle shaft bearing noise is similar to gear noise and differential pinion bearing whine. Axle shaft bearing noise 
will usually distinguish itself from gear noise by occurring in all driving modes (drive, coast, and float), and 
will persist with the transmission in NEUTRAL while the vehicle is moving at the speed in which the concern is 
occurring. If the vehicle makes this noise, remove the suspect axle shaft and install a new bearing and axle seal. 
Re-evaluate the vehicle for noise before removing any internal components. 

Bearing Rumble 

Bearing rumble sounds like marbles being tumbled. This condition is usually caused by a worn/damaged wheel 
bearing. The lower pitch is because the wheel bearing turns at only about one-third of the driveshaft speed. 
Wheel bearing noise also may be high-pitched, similar to gear noise, but will be evident in all four driving 
modes. 

Symptom Chart 

DRIVELINE ANGLES CURB SPECIFICATIONS 

Condition

Possible Sources

Action

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Traction-Lokohm 
Does Not Work 
in Snow, Mud or 
on Ice  

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Differential.  

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CARRY OUT the TRACTION-LOKohm 

DIFFERENTIAL OPERATION CHECK . 

REPAIR as necessary. REFER to REAR 

DRIVE AXLE/DIFFERENTIAL-FORD 

8.8-INCH or REAR DRIVE 

AXLE/DIFFERENTIAL-FORD 9.75-

INCH . 

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Lubricant 
Leaking from the 
Pinion Seal, Axle 
Shaft Oil Seals or 
Support Arm to 
the Housing  

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Vent.  

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Damage in the 

seal contact area 

or dust slinger on 

the pinion flange 

dust shield.  

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CLEAN the axle housing vent. 

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INSTALL a new pinion flange and the pinion 

seal if damage is found. 

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Front Axle Will 
Not Engage  

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Switches.  

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Wiring (DTC 

1844 or 1845).  

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Linkage.  

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REFER to TRANSFER CASE - GENERAL 

INFORMATION . 

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REFER to TRANSFER CASE - GENERAL 

INFORMATION . 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup

  

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Vacuum system.  

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Shift motor.  

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GO to PINPOINT TEST A . 

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Front Axle Will 
Not Disengage  

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Switches.  

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Wiring (DTC 

1844 or 1845).  

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Linkage.  

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Vacuum system.  

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Shift motor.  

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REFER to TRANSFER CASE - GENERAL 

INFORMATION . 

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REFER to TRANSFER CASE - GENERAL 

INFORMATION . 

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GO to PINPOINT TEST B . 

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Differential side 
gears/pinion gears 
are scored  

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Insufficient 
lubrication.  

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Incorrect or 

contaminated 

lubricant type.  

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INSTALL new gears. REFER to REAR 

DRIVE AXLE/DIFFERENTIAL-FORD 

8.8-INCH , REAR DRIVE 

AXLE/DIFFERENTIAL-FORD 9.75-INCH

or FRONT DRIVE 

AXLE/DIFFERENTIAL-FORD 8.8-INCH . 

FILL the axle to specification. 

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INSTALL new gears. REFER to REAR 

DRIVE AXLE/DIFFERENTIAL-FORD 

8.8-INCH , REAR DRIVE 

AXLE/DIFFERENTIAL-FORD 9.75-INCH

or FRONT DRIVE 

AXLE/DIFFERENTIAL-FORD 8.8-INCH . 

CLEAN and REFILL the axle to specification. 

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Axle overheating  

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Lubricant level 

too low.  

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Incorrect or 

contaminated 

lubricant type.  

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Bearing preload 

adjusted too tight. 

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Excessive gear 

wear.  

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Incorrect ring 

gear backlash.  

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CHECK the lubricant level. FILL the axle to 

specification. 

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INSPECT the axle for damage. REPAIR as 

necessary. CLEAN and REFILL the axle to 

specification. 

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CHECK the ring and pinion for damage. 

INSPECT the ring and pinion wear pattern. 

ADJUST the preload as necessary. 

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INSPECT all the axle gears for wear or 

damage. INSTALL new components as 

necessary. 

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INSPECT the ring gear for scoring. INSPECT 

the ring and pinion wear pattern. ADJUST the 

ring gear backlash as necessary. 

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Broken gear teeth 
on the ring gear 
or pinion  

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Overloading the 

vehicle.  

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INSTALL a new ring and pinion. REFER to 

REAR DRIVE AXLE/DIFFERENTIAL-

FORD 8.8-INCH , REAR DRIVE 

AXLE/DIFFERENTIAL-FORD 9.75-INCH

or FRONT DRIVE 

AXLE/DIFFERENTIAL-FORD 8.8-INCH . 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup

  

Pinpoint Tests 

PINPOINT TEST A: FRONT AXLE WILL NOT ENGAGE 

Fig. 22: Pinpoint Test A: Front Axle Will Not Engage Step (A1) 
Courtesy of FORD MOTOR CO. 

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Axle shaft broken 

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Overload the 

vehicle.  

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Misaligned axle 

shaft tube.  

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INSTALL a new axle shaft. REFER to REAR 

DRIVE AXLE/DIFFERENTIAL-FORD 

8.8-INCH , REAR DRIVE 

AXLE/DIFFERENTIAL-FORD 9.75-INCH

or FRONT DRIVE 

AXLE/DIFFERENTIAL-FORD 8.8-INCH . 

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INSPECT the axle for damage. CHECK axle 

shaft tube alignment. INSTALL a new axle 

shaft. REFER to REAR DRIVE 

AXLE/DIFFERENTIAL-FORD 8.8-INCH , 

REAR DRIVE AXLE/DIFFERENTIAL-

FORD 9.75-INCH or FRONT DRIVE 

AXLE/DIFFERENTIAL-FORD 8.8-INCH . 

 

2003 Ford Pickup F150 

2003 GENERAL INFORMATION Driveline System - General Information - F150 Pickup