Hydraulic Booster Diagnosis Erratic Operation
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
DEFINITION: Brake pedal sticks, binds, or grabs. | ||||
1 |
Did the pedal return to the same position? | -- | Go to Step 3 | Go to Step 2 |
2 | The brake pedal is sticking or binding. Repair the pedal as necessary. Is the repair complete? | -- | Go to Step 9 | -- |
3 | Do the brakes self-apply? | -- | Go to Step 4 | The condition is intermittent. Re-verify the condition. Go to Step 1 |
4 |
Verify the repair. Is the condition still present? | -- | Go to Step 5 | System OK |
5 |
Does the fluid surface in the forward reservoir show movement, or spouting? | -- | The condition is intermittent. Re-verify the condition. Go to Step 1 | Go to Step 6 |
6 | The hydraulic booster or the master cylinder is faulty. Determine if the master cylinder is faulty. Refer to Master Cylinder Diagnosis . Is the master cylinder faulty? | -- | Go to Step 7 | Go to Step 8 |
7 | Repair or replace the master cylinder as necessary. Refer to Master Cylinder Overhaul . Is the repair complete? | -- | Go to Step 9 | -- |
8 | Repair or replace the hydraulic booster as necessary. Refer to Power Brake Booster Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
9 | Verify the repair. Is the condition still present? | -- | Begin the diagnosis again. Go to Step 1 | System OK |
Hydraulic Booster Diagnosis Excessive Effort
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
If the power section is operating, holding the pedal requires less pressure. The pedal will fall slightly, then hold. Did the pedal fall slightly, then hold? | -- | ||
2 |
Are two or more brake applications power assisted? | -- | ||
3 | The accumulator is functioning properly. Perform the following test.
Important: Do not hold the brake pedal with 444 N (100 lb) for more than 5 seconds at a time. Did you find any leaks? | -- | ||
4 |
Does the brake pedal fall away? | -- | ||
5 | The hydraulic brake system is leaking. Refer to Brake Fluid Leak . Did you find and correct the condition? | -- | -- | |
6 | Repair or replace the hydraulic booster. Is the procedure complete? | -- | -- | |
7 | Check the fluid level of the power steering pump reservoir. Is the fluid level correct? | -- | ||
8 | Check the drive belt for wear and incorrect tension. Refer to Drive Belt Diagnosis . Did you find and correct a problem? | -- | ||
9 | Check the power steering pump speed. Is the pump speed slow? | -- | -- | |
10 |
Did you find and correct a problem? | -- | ||
11 | Perform the Power Steering Pump Flow and Relief Pressure Test. Refer to Power Steering System Test in Power Steering System. Is the pump output within specifications? | -- | ||
12 | Is the pump output low? | -- | ||
13 |
Is the procedure complete? | -- | -- | |
14 | Repair or replace the hydraulic booster. Refer to Power Brake Booster Replacement Is the procedure complete? | -- | -- | |
15 | Is the power steering pump reservoir fluid level low? | -- | ||
16 |
Important: Do not hold the brake pedal with 444 N (100 lb) for more than 5 seconds at a time. Did you find any leaks? | -- | -- | |
17 | Repair or replace any leaking components. Is the procedure complete? | -- | -- | |
18 | Verify the repair. Does the original condition still exist? | -- | System OK |
Hydraulic Booster Diagnosis General Diagnosis
Checks | Action |
|---|---|
Check for excessive seal friction in the booster. | Overhaul the booster. Use a new seal kit. |
Check for faulty spool action. | Flush the steering system while pumping the brake pedal. |
Check for a restriction in the return hose from the booster to the pump reservoir. | Replace the hose. |
Check for a damaged input rod end. | Replace the input rod. Replace the piston assembly. |
Checks | Action |
|---|---|
Check for faulty spool action, caused by contamination. | Flush the steering system while pumping the brake pedal. |
Check the power steering pump belt for slippage. | Refer to Drive Belt Diagnosis . |
Check for a low fluid level in the power steering pump. | Fill the reservoir. Check for external leaks. |
Checks | Action |
|---|---|
Check for contamination in the steering system. | Flush the steering system while pumping the brake pedal. |
Check for contamination in the booster system. | Flush the steering system while pumping the brake pedal. |
Check for internal leakage in the accumulator system. | Overhaul the accumulator. Use a rebuild kit and a seal kit. |
Checks | Action |
|---|---|
Check for contamination in the steering system. | Replace the hydraulic booster. Flush the complete system. |
Check for contamination in the booster system. | Replace the hydraulic booster. Flush the complete system. |
Check for a restriction in the return hose from the booster to the pump reservoir. | Replace the hose. |
