What Does It Mean?
This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Ford, Chevrolet, Chrysler, Dodge, Ford, Jeep, Hyundai, Honda, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
A stored P0649 code means that the Powertrain Control Module (PCM) has detected a malfunction in the cruise control indicator lamp circuit.
The cruise control indicator is located in the instrument cluster. Its main function is to alert the driver that the cruise control system has been activated (when illuminated). The cruise control system is also known as speed control.
The PCM typically monitors the continuity of the cruise control indicator lamp circuit whenever the ignition is turned on. The cruise control system uses input signals from the Vehicle Speed Sensor (VSS) and/or wheel speed sensors to automatically regulate the vehicle’s speed (after the system is activated by the driver).
Whenever the ignition is turned on and the PCM is powered up, several controller self-tests are performed. In addition to running internal controller self-tests, the Controller Area Network (CAN) transports serial data from each individual module to ensure that the onboard controllers interface correctly.
If a problem is detected in the monitoring of the cruise control indicator lamp circuit, a P0649 code will be stored and a Malfunction Indicator Lamp (MIL) may illuminate.
A style of cruise control indicator lamp:
P0649 Cruise Indicator
How Serious is this DTC?
All internal control module codes should be taken seriously. A stored P0649 code (with cruise control indicator lamp illuminated) will likely result in a loss of cruise control activation.
What are some of the symptoms of the code?
Symptoms of a P0649 trouble code may include:
Inoperative cruise control system
Other stored codes (cruise control related)
What are some of the common causes of the code?
Causes
of this code may include:
Faulty PCM
PCM programming error
Open or shorted cruise control indicator lamp circuit
Faulty cruise control indicator lamp bulb
What are the P0649 troubleshooting steps?
A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information will be needed to diagnose a P0649 code.
Consult your vehicle information source for Technical Service Bulletins (TSBs) that match the stored code, the vehicle (year, make, model, and engine), and the presented symptoms. If you find the relevant TSB, it may provide helpful diagnostic information.
Start by connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and freeze frame data. You’ll want to note this information, in case the code proves to be intermittent. After recording all relevant information, clear the codes and test-drive the vehicle until the code resets or the PCM enters readiness mode.
If the PCM enters readiness mode, the code is intermittent and will be more difficult to diagnose. The condition that caused the P0649 to be stored may need to worsen before an accurate diagnosis can be made. If the code resets, continue with your diagnosis.
Use your vehicle information source to obtain connector face views, connector pinout diagrams, component locators, wiring schematics, and diagnostic flowcharts related to the code and the specific vehicle.
Check for battery voltage at the cruise control warning indicator circuit using the appropriate wiring schematic and your DVOM. If not present, check the system fuses and relays and replace faulty parts as needed. If voltage is found at the cruise control warning indicator, suspect a faulty cruise control warning indicator bulb.
If the cruise control warning indicator bulb is functioning correctly and the P0649 continues to reset, use the DVOM to test the controller power fuses and relays. Replace blown fuses as needed. Fuses should be tested under load.
If all fuses and relays appear to be functioning correctly, a visual inspection of the wiring and harnesses related to the controller is necessary. You will also want to check the chassis and engine ground connections. Use your vehicle information source to obtain ground locations for the related circuits.
Visually inspect the system controllers for signs of water, heat, or collision damage. Any damaged controller, especially by water, should be considered faulty.
If the controller power and ground circuits are intact, suspect a faulty controller or a controller programming error. Replacing the controller will require reprogramming. In some cases, you can purchase pre-programmed controllers from aftermarket sources. Other vehicles/controllers will require onboard reprogramming that can only be performed by a dealer or another qualified source.
If the cruise control indicator does not illuminate during Key On Engine Off (KOEO), suspect a faulty cruise control warning indicator bulb
Test the integrity of the controller ground by connecting the DVOM’s negative test lead to ground and the positive test lead to battery voltage