P0656: Malfunction Indicator Lamp (MIL) Control Circuit Short to Battery

Definition

The OBD2 code P0656 indicates a malfunction in the Malfunction Indicator Lamp (MIL) control circuit, specifically a short to battery, which means the circuit is receiving an unintended voltage from the battery, potentially causing the MIL to function improperly

Common causes

Shorted wiring or connectors in the MIL control circuit
Faulty Engine Control Module (ECM)
Damaged or corroded connectors
Faulty MIL indicator bulb
Issues with the vehicle's ground connections
Malfunctioning relay or fuse related to the MIL circuit
Software issues in the ECM

Common misdiagnoses

Faulty Engine Control Module (ECM)
Bad wiring or connectors
Malfunctioning Malfunction Indicator Lamp (MIL)
Short circuit in the dashboard or instrument cluster
Issues with other sensor circuits
Battery or charging system problems
Faulty ground connections

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues
2. Inspect the MIL Circuit
3. Visually inspect the wiring and connectors associated with the MIL circuit. Look for signs of damage, corrosion, or loose connections
4. Pay special attention to the wiring harness that connects to the ECM and the MIL indicator on the dashboard
5. Test the MIL Bulb
6. Ensure that the MIL bulb is functioning correctly. If the bulb is burned out or not connected properly, it may cause the ECM to register a fault
7. Replace the bulb if necessary and check if the code persists
8. Check the ECM
9. Verify that the ECM is functioning properly. If the ECM is faulty, it may not be able to control the MIL circuit correctly
10. Check for any software updates or reprogramming that may be needed for the ECM
11. Test for Short Circuits
12. Use a multimeter to check for continuity in the MIL circuit. Look for any shorts to battery voltage or ground
13. Disconnect the battery and perform a resistance test on the circuit to identify any shorts
14. Inspect Ground Connections
15. Ensure that all ground connections related to the ECM and MIL circuit are clean and secure. Poor ground connections can lead to erratic behavior and false codes
16. Check for Voltage Supply
17. With the ignition on (engine off), use a multimeter to check for voltage at the MIL circuit. Ensure that the circuit is receiving the correct voltage as specified in the vehicle's service manual
18. Repair or Replace Faulty Components
19. If any damaged wiring, connectors, or components are found during the inspection, repair or replace them as necessary
20. If the ECM is determined to be faulty after testing, it may need to be replaced or reprogrammed
21. Clear the Codes and Test Drive
22. After making repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns
23. Consult a Professional
24. If the issue persists after following these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0656 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect the MIL Circuit

3. Visually inspect the wiring and connectors associated with the MIL circuit. Look for signs of damage, corrosion, or loose connections

4. Pay special attention to the wiring harness that connects to the ECM and the MIL indicator on the dashboard

5. Test the MIL Bulb

6. Ensure that the MIL bulb is functioning correctly. If the bulb is burned out or not connected properly, it may cause the ECM to register a fault

7. Replace the bulb if necessary and check if the code persists

8. Check the ECM

9. Verify that the ECM is functioning properly. If the ECM is faulty, it may not be able to control the MIL circuit correctly

10. Check for any software updates or reprogramming that may be needed for the ECM

11. Test for Short Circuits

12. Use a multimeter to check for continuity in the MIL circuit. Look for any shorts to battery voltage or ground

13. Disconnect the battery and perform a resistance test on the circuit to identify any shorts

14. Inspect Ground Connections

15. Ensure that all ground connections related to the ECM and MIL circuit are clean and secure. Poor ground connections can lead to erratic behavior and false codes

16. Check for Voltage Supply

17. With the ignition on (engine off), use a multimeter to check for voltage at the MIL circuit. Ensure that the circuit is receiving the correct voltage as specified in the vehicle's service manual

18. Repair or Replace Faulty Components

19. If any damaged wiring, connectors, or components are found during the inspection, repair or replace them as necessary

20. If the ECM is determined to be faulty after testing, it may need to be replaced or reprogrammed

21. Clear the Codes and Test Drive

22. After making repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

23. Consult a Professional

24. If the issue persists after following these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0656 code