My documentation indicates 4 flashes indicates the Vehicle Speed Sensor (VSS) or circuitry may be faulty or the cruise control speed control actuator itself may need attention.
Auto or manual vehicle? The VSS is located on the passenger side of the diff on manual gear boxes. If your speedometer isn't acting up, it's likely the VSS communication between the ECU and the speed control actuator. The actuator compares the speed recorded by the ECU against the desired cruise speed and opens the throttle accordingly.
The speed control actuator is behind the LH headlamp. Try removing and cleaning the electrical connector.
Wheel speed sensors are irrelevant; they are used by the ABS braking system, if fitted.