P0855: Drive Switch Input Circuit High

Definition

The OBD2 code P0855 indicates that the drive switch input circuit is reading a high voltage signal when it should not, suggesting a potential issue with the drive switch or its circuit

Common causes

Faulty drive switch
Wiring issues (shorts or open circuits)
Poor connections or corroded terminals
Malfunctioning transmission control module (TCM)
Faulty powertrain control module (PCM)
Software issues or glitches in the vehicle's computer system
Grounding problems in the circuit

Common misdiagnoses

Faulty transmission range sensor
Wiring issues or shorts in the circuit
Malfunctioning powertrain control module (PCM)
Incorrectly installed or damaged drive switch
Faulty neutral safety switch
Issues with the vehicle's battery or charging system
Misinterpretation of other related codes
Problems with the vehicle's ground connections

Troubleshooting steps

1. Check for Additional Codes

Before proceeding, check for any other related trouble codes that may provide more context to the issue
2. Inspect the Drive Switch
3. Locate the drive switch (often part of the transmission assembly)
4. Inspect the switch for any visible damage, corrosion, or loose connections
5. Test the Drive Switch
6. Use a multimeter to test the drive switch's resistance and ensure it operates within the manufacturer's specifications
7. Check for continuity in the switch when it is in different positions (e.g., park, neutral, drive)
8. Inspect Wiring and Connectors
9. Examine the wiring harness and connectors leading to the drive switch for any signs of wear, fraying, or damage
10. Ensure that all connections are secure and free of corrosion
11. Check for Short Circuits
12. Use a multimeter to check for shorts in the wiring that could cause the signal to be higher than expected
13. Inspect the wiring for any signs of pinching or contact with hot surfaces
14. Test the Transmission Control Module (TCM)
15. If the drive switch and wiring are in good condition, the issue may lie with the TCM
16. Check for proper operation and any software updates that may be needed
17. Clear the Codes and Test Drive
18. After performing the above checks and repairs, clear the trouble codes using an OBD-II scanner
19. Take the vehicle for a test drive to see if the code reappears
20. Refer to the vehicle's service manual for specific testing procedures and specifications related to the drive switch and TCM
21. Seek Professional Help
22. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the P0855 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect the Drive Switch

3. Locate the drive switch (often part of the transmission assembly)

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

5. Test the Drive Switch

6. Use a multimeter to test the drive switch's resistance and ensure it operates within the manufacturer's specifications

7. Check for continuity in the switch when it is in different positions (e.g., park, neutral, drive)

8. Inspect Wiring and Connectors

9. Examine the wiring harness and connectors leading to the drive switch for any signs of wear, fraying, or damage

10. Ensure that all connections are secure and free of corrosion

11. Check for Short Circuits

12. Use a multimeter to check for shorts in the wiring that could cause the signal to be higher than expected

13. Inspect the wiring for any signs of pinching or contact with hot surfaces

14. Test the Transmission Control Module (TCM)

15. If the drive switch and wiring are in good condition, the issue may lie with the TCM

16. Check for proper operation and any software updates that may be needed

17. Clear the Codes and Test Drive

18. After performing the above checks and repairs, clear the trouble codes using an OBD-II scanner

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

20. Refer to the vehicle's service manual for specific testing procedures and specifications related to the drive switch and TCM

21. Seek Professional Help

22. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the P0855 code