Supporting Member (Lifetime)
Join Date: Jun 2005
Location: Fountain Valley, CA
U0126 - lost communication with steering angle sensor
DTCs RELATED TO BATTERY VOLTAGE, IGNITION, OR VIN MESSAGES
CAN C BUS CIRCUITS OPEN OR SHORTED
STEERING ANGLE SENSOR POWER AND GROUND
STEERING ANGLE SENSOR
ANTI-LOCK BRAKES MODULE
U0100-LOST COMMUNICATION WITH ECM/PCM
CAN B OR CAN C BUS CIRCUITS OPEN OR SHORTED
DTCS RELATED TO BATTERY VOLTAGE, IGNITION, OR VIN MESSAGES
FCM NOT CONFIGURED CORRECTLY
ECM/PCM POWER AND GROUND
MODULE THAT SET THIS DTC
B121A - RIGHT HEATED SEAT HI INDICATOR CONTROL CIRCUIT HIGH
Possible causes: (P84) RIGHT HEATED SEAT HIGH INDICATOR DRIVER CIRCUIT SHORTED TO BATTERY
RIGHT HEATED SEAT SWITCH
Sounds like both U0100 and U0126 could be due to the steering column module (SCM) being incorrectly connected or defective. If the SCM isn't connected or working, you'd lose anything on the "driver's" side of the SCM, such as the steering wheel controls, horn, cruise control, turn signals, air bag, high beams, and wipers. Sounds like it matches your symptoms. Have you done any work around the steering wheel/steering column recently? If you have a telescoping steering column, try unlocking it and pushing it back in towards the dashboard (retracted position) to see if this makes a difference.
If the steering angle sensor can't be read, the traction control system won't be properly operational since it needs to know which way the wheels are turned to be able to properly modulate the brakes.
Not sure on the B121 codes.