B1985: Seat Switch Lumbar Deflate Circuit Failure

Definition

The OBD2 code B1985 indicates a malfunction in the lumbar deflate circuit of the seat switch, which may prevent the lumbar support from deflating properly

Common causes

Faulty seat switch
Damaged wiring or connectors
Short circuit in the lumbar deflate circuit
Failed lumbar support actuator
Poor ground connection
Corrosion in electrical connections
Malfunctioning control module

Common misdiagnoses

Faulty seat switch
Wiring issues or shorts in the seat harness
Defective lumbar support actuator
Malfunctioning body control module (BCM)
Incorrectly calibrated seat position sensors
Issues with the power supply to the seat system
Software glitches in the vehicle's control modules

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are multiple issues
2. Inspect the Seat Switch
3. Remove the seat cover or access panel to inspect the lumbar support switch
4. Check for any visible damage, corrosion, or loose connections at the switch
5. Test the Lumbar Support Switch
6. Use a multimeter to test the switch for continuity. Ensure that it operates correctly when pressed
7. If the switch is faulty, it may need to be replaced
8. Check Wiring and Connectors
9. Inspect the wiring harness and connectors leading to the lumbar support motor and switch for any signs of damage, fraying, or corrosion
10. Repair or replace any damaged wiring or connectors
11. Test the Lumbar Support Motor
12. If the switch and wiring are in good condition, test the lumbar support motor itself
13. Apply direct power to the motor to see if it operates. If it does not, the motor may be faulty and require replacement
14. Inspect the Control Module
15. If all components appear to be functioning correctly, the issue may lie within the vehicle's control module
16. Check for software updates or reprogramming needs, as sometimes a reset can resolve communication issues
17. Clear Codes and Test Drive
18. After performing repairs or replacements, clear the trouble codes using the OBD-II scanner
19. Take the vehicle for a test drive to see if the code returns
20. Refer to the vehicle's service manual for specific diagnostic procedures and wiring diagrams related to the lumbar support system
21. Seek Professional Help
22. If the issue persists after performing these steps, it may be best to consult a professional mechanic or dealership for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the B1985 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect the Seat Switch

3. Remove the seat cover or access panel to inspect the lumbar support switch

4. Check for any visible damage, corrosion, or loose connections at the switch

5. Test the Lumbar Support Switch

6. Use a multimeter to test the switch for continuity. Ensure that it operates correctly when pressed

7. If the switch is faulty, it may need to be replaced

8. Check Wiring and Connectors

9. Inspect the wiring harness and connectors leading to the lumbar support motor and switch for any signs of damage, fraying, or corrosion

10. Repair or replace any damaged wiring or connectors

11. Test the Lumbar Support Motor

12. If the switch and wiring are in good condition, test the lumbar support motor itself

13. Apply direct power to the motor to see if it operates. If it does not, the motor may be faulty and require replacement

14. Inspect the Control Module

15. If all components appear to be functioning correctly, the issue may lie within the vehicle's control module

16. Check for software updates or reprogramming needs, as sometimes a reset can resolve communication issues

17. Clear Codes and Test Drive

18. After performing repairs or replacements, clear the trouble codes using the OBD-II scanner

19. Take the vehicle for a test drive to see if the code returns

20. Refer to the vehicle's service manual for specific diagnostic procedures and wiring diagrams related to the lumbar support system

21. Seek Professional Help

22. If the issue persists after performing these steps, it may be best to consult a professional mechanic or dealership for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the B1985 code