The P0649 trouble code indicates an issue with the speed control lamp control circuit. The speed control lamp is part of the vehicle’s cruise control system and is designed to illuminate when the cruise control system is active. This code is set when the engine control module (ECM) detects a malfunction in the circuit responsible for controlling the speed control lamp.
P0649 Speed Control Lamp Control Circuit
Code symptoms P0649.
1. Illumination of the speed control lamp when the cruise control system is not engaged.
2. Inoperative cruise control system.
3. Malfunction indicator lamp (MIL) or check engine light (CEL) may be illuminated.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0649.
1. Faulty speed control lamp.
2. Open or short circuit in the speed control lamp control circuit.
3. Wiring or connector issues in the speed control lamp control circuit.
4. Faulty cruise control module or ECM.
Code Solutions P0649.
1. Inspect the speed control lamp and replace it if it is found to be faulty.
2. Check the wiring and connectors in the speed control lamp control circuit for any signs of damage, corrosion, or loose connections. Repair or replace damaged components as necessary.
3. Clear the trouble codes and perform a test drive to verify that the issue has been resolved. If the code persists, further diagnosis may be required, including testing the voltage output of the cruise control module and the speed control lamp control circuit.
4. Ensure that the vehicle’s battery is in good condition and fully charged, as low voltage can sometimes trigger false trouble codes related to the cruise control system.
5. Follow manufacturer-specific diagnostic procedures outlined in the vehicle’s service manual to accurately diagnose and repair issues related to the speed control lamp control circuit. If needed, seek assistance from a qualified technician or dealership.