I have a 2003 Ranger 4X4 with ABS, the brakes peddle has become very hard, almost like I no longer have power brakes. I have had a similar problem with another car and changed the booster and the problem was solved. My truck is nearing 150K miles and still going strong but I thought I would change the booster and the master cylinder and the problem is still there. If I stand on the brakes the wheels try to lock up and the ABS does kick but I have to push hard, even in dirt. I am thinking it might be a wheel sensor or the ABS module. Any ideas, anyone else have this problem.

Thanks,

 

make sure you are getting vacuum to the booster. I had that happen once. Fitting on manifold plugged up with carbon.

 

Thanks, I finally got a chance to check the vacuum, its clear and I have good vacuum at the booster. I also checked the booster and it holds a vacuum. Any one have another suggestions?

 

Possible check valve issue? This is from my Ford Manual:

Condition: Excessive Brake Pedal Effort

Possible Sources:

- Power brake booster.
- Power brake booster check valve
- Power brake booster hose.

Action: PERFORM the brake booster component tests in this section.

Component Tests

Brake Booster

1. Check the hydraulic brake system for leaks or insufficient fluid.
2. With the transmission (7003) in NEUTRAL, stop the engine (6007) and apply the parking brake control (2780). 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 (2A047) 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 above.
5. CHECK and if no downward movement of the brake pedal is felt, replace the 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 89 N (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), replace the check valve and retest. If the brake pedal feels spongy, bleed the hydraulic system to remove air. Refer to Bleeding—System in this section.

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:

- Start and run the engine for at least 10 seconds.
- Operate the brake pedal to check for power assist.
- Disconnect the vacuum booster hose from the power brake booster. Do not remove the power brake booster check valve from the power brake booster.
- There should be enough vacuum retained in the power brake booster for at least one more power-assisted brake operation.

 

Checked all of that, It seems that the booster is doing what it is supposed to do. After driving the back brake drums are not too hot, just warm while you could cook on the front disk, I'm thinking the the back brakes are not engaging completely could this have anything to do with the abs?

 

The rears don't see a lot of action. Fronts will be very hot. I would get some one to help bleed these brakes and see if every cylinder is moving fluid.