Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSUBARU2002LEGACY L SEDAN AWD F4-2.5L SOHCREPAIR AND DIAGNOSISRELAYS AND MODULESRELAYS AND MODULES - BRAKES AND TRACTION CONTROLELECTRONIC BRAKE CONTROL MODULETESTING AND INSPECTIONABS
2002 Subaru Legacy L Sedan AWD F4-2.5L SOHC
ABS
2002 Subaru Legacy L Sedan AWD F4-2.5L SOHCSECTION ABS
INSPECTION
1. Check connected and fixed condition of connector.
1 of 2
2 of 2
2. Check specifications of the mark with ABSCM & H/U.
1. CHECKING THE HYDRAULIC UNIT ABS OPERATION BY PRESSURE GAUGE
1. Lift-up vehicle and remove wheels.
2. Disconnect the air bleeder screws from the FL and FR caliper bodies.
3. Connect two pressure gauges to the FL and FR caliper bodies.
CAUTION:
^ Pressure gauges used exclusively for brake fluid must be used.
^ Do not employ pressure gauge previously used for transmission since the piston seal is expanded which may lead to malfunction of the brake.
NOTE: Wrap sealing tape around the pressure gauge.
4. Bleed air from the pressure gauges.
5. Perform ABS sequence control.
6. When the hydraulic unit begins to work, and first the FL side performs decompression, holding, and compression, and then the FR side performs decompression, holding, and compression.
7. Read values indicated on the pressure gauge and check if the fluctuation of the values between decompression and compression meets the standard values. Also check if any irregular brake pedal tightness is felt.
8. Remove pressure gauges from FL and FR caliper bodies.
9. Remove air bleeder screws from the RL and RR caliper bodies.
10. Connect the air bleeder screws to the FL and FR caliper bodies.
11. Connect two pressure gauges to the RL and RR caliper bodies.
12. Bleed air from the pressure gauges and the FL and FR caliper bodies.
13. Perform ABS sequence control.
14. When the hydraulic unit begins to work, at first the RR side performs decompression, holding, and compression, land then the RL side performs decompression, holding, and compression.
15. Read values indicated on the pressure gauges and check if they meet the standard value.
16. After checking, remove the pressure gauges from caliper bodies.
17. Connect the air bleeder screws to RL and RR caliper bodies.
18. Bleed air from brake line.
2. CHECKING THE HYDRAULIC UNIT ABS OPERATION WITH BRAKE TESTER
1. In the case of AWD AT vehicles, install a spare fuse with the FWD connector in the main fuse box to simulate FWD vehicles.
2. Prepare for operating ABS sequence control.
1 of 2
2 of 2
3. Set the front wheels or rear wheels on the brake tester and set the select lever's position at "neutral".
4. Operate the brake tester.
5. Perform ABS sequence control.
6. Hydraulic unit begins to work; and check the following working sequence.
1. The FL wheel performs decompression, holding, and compression in sequence, and subsequently the FR wheel repeats the cycle.
2. The RR wheel performs decompression, holding, and compression in sequence, and subsequently the RL wheel repeats the cycle.
7. Read values indicated on the brake tester and check if the fluctuation of values, when decompressed and compressed, meet the standard values.
8. After checking, also check if any irregular brake pedal tightness is felt.
1. Check connected and fixed condition of connector.
1 of 2
2 of 2
2. Check specifications of the mark with ABSCM & H/U.
1. CHECKING THE HYDRAULIC UNIT ABS OPERATION BY PRESSURE GAUGE
1. Lift-up vehicle and remove wheels.
2. Disconnect the air bleeder screws from the FL and FR caliper bodies.
3. Connect two pressure gauges to the FL and FR caliper bodies.
CAUTION:
^ Pressure gauges used exclusively for brake fluid must be used.
^ Do not employ pressure gauge previously used for transmission since the piston seal is expanded which may lead to malfunction of the brake.
NOTE: Wrap sealing tape around the pressure gauge.
4. Bleed air from the pressure gauges.
5. Perform ABS sequence control.
6. When the hydraulic unit begins to work, and first the FL side performs decompression, holding, and compression, and then the FR side performs decompression, holding, and compression.
7. Read values indicated on the pressure gauge and check if the fluctuation of the values between decompression and compression meets the standard values. Also check if any irregular brake pedal tightness is felt.
8. Remove pressure gauges from FL and FR caliper bodies.
9. Remove air bleeder screws from the RL and RR caliper bodies.
10. Connect the air bleeder screws to the FL and FR caliper bodies.
11. Connect two pressure gauges to the RL and RR caliper bodies.
12. Bleed air from the pressure gauges and the FL and FR caliper bodies.
13. Perform ABS sequence control.
14. When the hydraulic unit begins to work, at first the RR side performs decompression, holding, and compression, land then the RL side performs decompression, holding, and compression.
15. Read values indicated on the pressure gauges and check if they meet the standard value.
16. After checking, remove the pressure gauges from caliper bodies.
17. Connect the air bleeder screws to RL and RR caliper bodies.
18. Bleed air from brake line.
2. CHECKING THE HYDRAULIC UNIT ABS OPERATION WITH BRAKE TESTER
1. In the case of AWD AT vehicles, install a spare fuse with the FWD connector in the main fuse box to simulate FWD vehicles.
2. Prepare for operating ABS sequence control.
1 of 2
2 of 2
3. Set the front wheels or rear wheels on the brake tester and set the select lever's position at "neutral".
4. Operate the brake tester.
5. Perform ABS sequence control.
6. Hydraulic unit begins to work; and check the following working sequence.
1. The FL wheel performs decompression, holding, and compression in sequence, and subsequently the FR wheel repeats the cycle.
2. The RR wheel performs decompression, holding, and compression in sequence, and subsequently the RL wheel repeats the cycle.
7. Read values indicated on the brake tester and check if the fluctuation of values, when decompressed and compressed, meet the standard values.
8. After checking, also check if any irregular brake pedal tightness is felt.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.