B1807: Lamp Tail Output Circuit Open

Definition

The OBD2 code B1807 indicates that there is an open circuit in the tail lamp output circuit, meaning the system is not detecting the expected electrical connection or signal for the tail lights

Common causes

Open circuit in the tail lamp wiring
Faulty tail lamp bulb
Corroded or damaged connectors
Defective tail lamp assembly
Faulty body control module (BCM)
Poor ground connection
Damaged wiring harness

Common misdiagnoses

Faulty tail light bulbs
Bad tail light sockets
Damaged wiring or connectors
Faulty body control module (BCM)
Incorrectly installed or loose connections
Issues with the vehicle's ground connections
Malfunctioning switch or relay related to the tail lights

Troubleshooting steps

1. Check the Vehicle's Manual

Refer to the vehicle's service manual for specific information regarding the B1807 code and the tail lamp circuit layout
2. Visual Inspection
3. Inspect the tail lamp assembly for any visible damage or corrosion
4. Check the wiring harness and connectors for signs of wear, fraying, or disconnection
5. Ensure that the tail lamp bulbs are properly seated and not burnt out
6. Test the Tail Lamp Bulbs
7. Remove the tail lamp bulbs and test them with a multimeter or replace them with known good bulbs to ensure they are functioning properly
8. Check Fuses
9. Locate the fuse box and check for any blown fuses related to the tail lamp circuit. Replace any blown fuses and retest
10. Inspect the Wiring
11. Use a multimeter to check for continuity in the tail lamp circuit wiring. Look for any breaks or shorts in the wires
12. Check for proper grounding at the tail lamp assembly. A poor ground connection can cause circuit issues
13. Test the Tail Lamp Relay
14. If applicable, test the tail lamp relay to ensure it is functioning correctly. Replace it if necessary
15. Scan for Additional Codes
16. Use an OBD-II scanner to check for any additional trouble codes that may provide more context to the issue
17. Check the Body Control Module (BCM)
18. If all other components are functioning correctly, the issue may lie within the BCM. Check for any software updates or faults in the module
19. Perform a Circuit Test
20. With the vehicle in the "on" position, use a multimeter to check for voltage at the tail lamp connector. If there is no voltage, trace the circuit back to find the open
21. Consult a Professional
22. If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician who has experience with electrical systems and OBD-II diagnostics. By following these steps, you should be able to identify and resolve the issue related to the B1807 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check the Vehicle's Manual

2. Visual Inspection

3. Inspect the tail lamp assembly for any visible damage or corrosion

4. Check the wiring harness and connectors for signs of wear, fraying, or disconnection

5. Ensure that the tail lamp bulbs are properly seated and not burnt out

6. Test the Tail Lamp Bulbs

7. Remove the tail lamp bulbs and test them with a multimeter or replace them with known good bulbs to ensure they are functioning properly

8. Check Fuses

9. Locate the fuse box and check for any blown fuses related to the tail lamp circuit. Replace any blown fuses and retest

10. Inspect the Wiring

11. Use a multimeter to check for continuity in the tail lamp circuit wiring. Look for any breaks or shorts in the wires

12. Check for proper grounding at the tail lamp assembly. A poor ground connection can cause circuit issues

13. Test the Tail Lamp Relay

14. If applicable, test the tail lamp relay to ensure it is functioning correctly. Replace it if necessary

15. Scan for Additional Codes

16. Use an OBD-II scanner to check for any additional trouble codes that may provide more context to the issue

17. Check the Body Control Module (BCM)

18. If all other components are functioning correctly, the issue may lie within the BCM. Check for any software updates or faults in the module

19. Perform a Circuit Test

20. With the vehicle in the "on" position, use a multimeter to check for voltage at the tail lamp connector. If there is no voltage, trace the circuit back to find the open

21. Consult a Professional

22. If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician who has experience with electrical systems and OBD-II diagnostics. By following these steps, you should be able to identify and resolve the issue related to the B1807 code