The Plus one is the steering controller that provides the EDX/XC with feedback from the wheel angle sensor (WAS) , valve and steering wheel switch. When the Plus1 has a fault, it will throw a code. There will be a red flashing light. The red light will blink 2 times, pause, then blink between 1 to 9 times. There can be multiple codes.
21. WAS above normal operating range- Adjust sensor to allow values below 4750
22. WAS below normal operating range- Adjust sensor to allow values above 250
23. Sensor power out of range- Repair/Replace sensor power wiring
24. Steer left Open/Short- Either plug in left coil cable or cable is bad
25. Steer Right Open/ Short- Either plug in right coil cable or cable is bad
26. Enable valve open/short- Either plug in enable valve cable or cable is bad
29. Reset required- Reboot the Plus1 steering controller/replace Plus1
Example: codes 21, and 29.