C1103: ABS Hydraulic Brake Switch Circuit Failure

Definition

The OBD2 code C1103 indicates a failure in the ABS hydraulic brake switch circuit, which may affect the operation of the anti-lock braking system

Common causes

Faulty brake switch
Wiring issues (shorts or open circuits)
Corroded connectors
Failed ABS control module
Low brake fluid level
Malfunctioning hydraulic control unit
Poor ground connection

Common misdiagnoses

Faulty ABS module
Bad wheel speed sensors
Malfunctioning brake pedal switch
Wiring issues or shorts in the circuit
Faulty brake booster
Low brake fluid level
Defective master cylinder
Incorrectly installed or damaged ABS pump

Troubleshooting steps

1. Check the Brake Switch
2. Inspect the brake light switch for proper operation. Ensure that it is not stuck or malfunctioning
3. Test the switch with a multimeter to confirm it opens and closes correctly when the brake pedal is pressed and released
4. Inspect Wiring and Connectors
5. Examine the wiring and connectors associated with the ABS hydraulic brake switch for any signs of damage, corrosion, or loose connections
6. Repair or replace any damaged wiring or connectors
7. Check ABS Module
8. Ensure that the ABS control module is functioning correctly. If there are other codes present, they may provide additional insight into the issue
9. If necessary, perform a reset or reprogram the ABS module
10. Test the ABS Hydraulic Unit
11. Inspect the ABS hydraulic unit for any leaks or damage. Ensure that it is properly connected and functioning
12. If the unit is faulty, it may need to be repaired or replaced
13. Scan for Additional Codes
14. Use an OBD-II scanner to check for any additional trouble codes that may be related to the ABS system. Addressing these codes may help resolve the C1103 code
15. Check for Ground Issues
16. Ensure that the ABS system has a good ground connection. A poor ground can cause various electrical issues, including circuit failures
17. Inspect Fuses
18. Check the fuses related to the ABS system and brake lights. Replace any blown fuses
19. Perform a Visual Inspection
20. Look for any signs of physical damage to the ABS components, including the hydraulic pump, valves, and associated wiring
21. Consult Technical Service Bulletins (TSBs)
22. Check for any manufacturer-specific TSBs related to the C1103 code or ABS system issues. There may be known fixes or recalls
23. Professional Diagnosis
24. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or an automotive technician with experience in ABS systems. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the C1103 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check the Brake Switch

2. Inspect the brake light switch for proper operation. Ensure that it is not stuck or malfunctioning

3. Test the switch with a multimeter to confirm it opens and closes correctly when the brake pedal is pressed and released

4. Inspect Wiring and Connectors

5. Examine the wiring and connectors associated with the ABS hydraulic brake switch for any signs of damage, corrosion, or loose connections

6. Repair or replace any damaged wiring or connectors

7. Check ABS Module

8. Ensure that the ABS control module is functioning correctly. If there are other codes present, they may provide additional insight into the issue

9. If necessary, perform a reset or reprogram the ABS module

10. Test the ABS Hydraulic Unit

11. Inspect the ABS hydraulic unit for any leaks or damage. Ensure that it is properly connected and functioning

12. If the unit is faulty, it may need to be repaired or replaced

13. Scan for Additional Codes

14. Use an OBD-II scanner to check for any additional trouble codes that may be related to the ABS system. Addressing these codes may help resolve the C1103 code

15. Check for Ground Issues

16. Ensure that the ABS system has a good ground connection. A poor ground can cause various electrical issues, including circuit failures

17. Inspect Fuses

18. Check the fuses related to the ABS system and brake lights. Replace any blown fuses

19. Perform a Visual Inspection

20. Look for any signs of physical damage to the ABS components, including the hydraulic pump, valves, and associated wiring

21. Consult Technical Service Bulletins (TSBs)

22. Check for any manufacturer-specific TSBs related to the C1103 code or ABS system issues. There may be known fixes or recalls

23. Professional Diagnosis

24. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or an automotive technician with experience in ABS systems. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the C1103 code