2008 Chrysler Caliber P2004 Fault: Runner Control Replacement and Signal Troubleshooting

Happy New Year! I recently replaced the runner control unit in my 2008 Chrysler Caliber. Last month, after replacing two runner controls (purchased new but appeared to have been previously mounted), the OBD2 scanner returned code P2004 repeatedly. The issue persists even after resetting the system. I've checked the wiring: the yellow wire shows 5V with a signal of 0.05V, and the blue wire receives correct power. However, I'm unsure whether the system is receiving the proper signal to activate the flaps. Based on my previous experience during the replacement, the flap mechanism appears free and functional. I'm seeking advice on how to properly diagnose whether the runner control unit is receiving a valid signal or if there's an underlying issue with the sensor or wiring. The car has been driven about 20 miles without resolving the code. I plan to schedule a professional inspection soon—just hoping it doesn't take until after New Year. Any insights, troubleshooting steps, or recommendations would be greatly appreciated.