The P0649: Speed Control Lamp Control Circuit code refers to a malfunction in the speed control (cruise control) lamp control circuit. This circuit is responsible for illuminating the speed control lamp to indicate the system’s status. The issue may stem from a faulty control circuit, wiring problems, or a defective speed control lamp.
P0649 – Quick Overview
Code | Information |
---|---|
Meaning | P0649: Speed Control Lamp Control Circuit |
Is it serious? | No, but it can prevent the driver from knowing the status of the speed control system. |
Possible causes | – Faulty speed control lamp control circuit – Wiring issue – Faulty speed control lamp |
How to diagnose? | – Test speed control lamp control circuit – Inspect wiring and connectors – Replace speed control lamp if necessary |
P0649 Meaning
The P0649 code indicates a problem in the circuit that controls the speed control (cruise control) lamp. This lamp informs the driver when the speed control system is active. If the circuit is malfunctioning, the driver may not know when the cruise control is engaged or disengaged, potentially leading to confusion.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for additional codes that may be related to the speed control system or electrical faults. | OBD-II Scanner |
Test the Speed Control Lamp Control Circuit | Use a multimeter to test the voltage and functionality of the speed control lamp control circuit to ensure it is operating within specifications. | Multimeter |
Inspect Wiring and Connectors | Inspect the wiring and connectors for signs of damage, loose connections, or corrosion that may be affecting the speed control lamp circuit. | Flashlight, Multimeter |
Test the Speed Control Lamp | Test the speed control lamp itself to verify whether it is functioning correctly. If it fails to illuminate, replace the lamp. | Diagnostic Tool, Multimeter |
Replace the Speed Control Lamp if Necessary | If the speed control lamp is faulty or not working, replace it to restore proper system functionality. | Replacement Lamp, Tools |
Clear the Code and Test | After repairs, clear the code using an OBD-II scanner and test the vehicle to ensure the speed control lamp functions correctly. | OBD-II Scanner, Vehicle Manual |

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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)