Ford F150 Pickup. Instruction - part 388

brake drum. On F150 Pickup and F150 Heritage Pickup with drum brakes, using parking brake adjuster screw, 
adjust parking brake shoe and lining until they drag against parking brake drum. On models with rear disc 
brakes, adjust parking brake shoe and lining to 0.020" (0.51 mm) less than drum measurement. Replace the 
parking brake shoes if the linings have worn to within 0.04" (1.0 mm) of the shoe. On all models, check the 
parking brake by depressing the parking brake control pedal. The parking brake must be fully set by applying 
pressure to the pedal before it reaches a mechanical stop. If not as specified, install a new parking brake 
control/cables as necessary. 

VACUUM POWER BOOSTER PUSH ROD 

1. Push rod has an adjustment screw to maintain correct distance between booster push rod and master 

cylinder piston. If push rod is adjusted too long, it prevents master cylinder piston from completely 
releasing hydraulic pressure, causing brakes to drag. If push rod is adjusted too short, it causes excessive 
pedal travel and an undesirable groaning noise in booster area.  

2. Adjust the power brake booster to brake master cylinder push rod length. Remove master cylinder. 

Measure the power brake booster to brake master cylinder pushrod with engine running (vacuum 
applied). See Fig. 20 . If necessary, adjust the screw to the correct length. 

CAUTION: Do not apply the brake pedal with the master cylinder removed.

 

2003 Ford Pickup F150 

2002-04 BRAKES Disc & Drum - Blackwood, F150 Heritage Pickup & F150 Pickup

  

Fig. 20: Adjusting Power Brake Booster Push Rod 
Courtesy of FORD MOTOR CO. 

COMPONENT TESTS 

MASTER CYLINDER 

Bypass Condition Test 

1. Disconnect the brake lines at the brake master cylinder.  

2. Plug the outlet ports of the brake master cylinder.  

3. Apply the brakes. If brake pedal height cannot be maintained, the brake master cylinder has an internal 

leak and must be rebuilt or a new master cylinder installed.  

Compensator Port Check 

The purpose of the compensator ports in the brake master cylinder is to supply any additional brake fluid 
required by the system due to brake pad wear and to allow brake fluid returning from the brake lines to the 
brake master cylinder to enter the brake master cylinder reservoir. The returning brake fluid will cause a slight 
turbulence in the brake master cylinder reservoir. Turbulence seen in the brake master cylinder reservoir upon 

 

2003 Ford Pickup F150 

2002-04 BRAKES Disc & Drum - Blackwood, F150 Heritage Pickup & F150 Pickup

  

application or release of the brake pedal is normal and shows that the compensating ports are not plugged.

POWER BRAKE BOOSTER 

1. Check the hydraulic brake system for leaks or insufficient fluid.  

2. With the transmission in Neutral, stop the engine and apply the parking brake control. Apply the brake 

pedal several times to exhaust all vacuum in the system.  

3. Apply the brake pedal and hold it in the applied position. Start the engine. If the vacuum system is 

operating, the brake pedal will tend to move downward under constant foot pressure. If no motion is felt, 
the power brake booster system is not functioning. Continue the test with the following steps.  

4. Remove the vacuum booster hose from check valve connection. Manifold vacuum must be available at 

the check valve end of the vacuum booster hose with the engine at idle speed and the transmission in 
Neutral. If the manifold vacuum is available to the power brake booster, connect the vacuum booster hose 
to the power brake booster check valve and repeat Steps 2 and 3 .  

5. Check and if no downward movement of the brake pedal is felt, install a new power brake booster.  

6. Operate the engine a minimum of 10 seconds at fast idle. Stop the engine, and let the vehicle stand for 10 

minutes. Then apply the brake pedal with approximately 20 lbs. of force. The brake pedal feel should be 
the same as that noted with the engine operating. If the brake pedal feels hard (no power assist), install a 
new check valve and retest. If the brake pedal feels spongy, bleed the hydraulic system to remove air. See 
BLEEDING BRAKE SYSTEM .  

POWER BRAKE BOOSTER CHECK VALVE 

The function of the power brake booster check valve is to allow manifold vacuum to enter the power brake 
booster and prevent the escape of vacuum in case manifold vacuum is lost during sustained full throttle 
operation. To test the function of the power brake booster check valve:  

z

Start and run the engine for at least 10 seconds.  

z

Operate the brake pedal to check for power assist. Disconnect the vacuum booster hose from the power 
brake booster.  

z

Do not remove the power brake booster check valve from the power brake booster.  

z

There should be enough vacuum retained in the power brake booster for at least one more power-assisted 
brake operation.  

REMOVAL & INSTALLATION 

BACKING PLATE (F150 HERITAGE PICKUP & F150 PICKUP) 

Removal & Installation 

1. Remove brake shoes. See REAR BRAKE SHOES (F150 HERITAGE PICKUP & F150 PICKUP ) . 

CAUTION: Anti-lock brake systems operate under high pressure. Before servicing, 

system pressure must be discharged. See appropriate ANTI-LOCK article.

 

2003 Ford Pickup F150 

2002-04 BRAKES Disc & Drum - Blackwood, F150 Heritage Pickup & F150 Pickup

  

2. Remove wheel cylinder. See WHEEL CYLINDERS .  

3. Remove differential housing cover. Drain differential fluid into approved clean container for reuse. Clean 

gasket mating surface of rear axle and differential housing cover.  

4. Remove the differential pinion shaft lock bolt. Remove the differential pinion shaft. See Fig. 21 .  

5. Push the axle shafts inboard. Remove the "U" washers. See Fig. 22 .  

6. Using caution as to not damage the seal, remove the axle shaft or the axle shaft and rear hub, if so 

equipped. See Fig. 23 .  

7. Compress the cable retainer and pull the parking brake rear cable and conduit from the brake backing 

plate. See Fig. 24 .  

8. Remove the four backing plate-to-axle flange nuts and bolts and the brake backing plate. See Fig. 25 .  

9. To install, reverse removal order. Apply a new continuous bead of sealant to the differential housing 

cover. See Fig. 26 .  

10. Fill differential with of Motorcraft SAE 75W140 High Performance Synthetic Rear Axle Lubricant 

(F1TZ-19580-B) until fluid level is about 1/4" below bottom of filler plug hole. To complete installation, 
reverse removal procedures.  

Fig. 21: Identifying Differential Pinion Shaft & Lock Bolt 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2002-04 BRAKES Disc & Drum - Blackwood, F150 Heritage Pickup & F150 Pickup