Code C0561 comes in two forms.
C0561-71 System disabled Information stored invalid serial data received
C0561-72 System disabled Information stored alive counter incorrect.
C codes are considered “chassis” code. This particular code is for GM and relates to the traction control system. The traction control system gets its data from the ABS system. When it detects one wheel spinning faster than the others, or one wheel locking up, it activates the traction control system. Depending on the generation of traction control, the system will activate the ABS brakes to reduces spinning, or, in later models can actually reduce engine power. Late model systems include yaw sensors and steering position sensors to detect the difference between the driver’s intention from the steering wheel and the actually direction the vehicle is moving.
In the case of this GM code, the electronic brake control module (EBCM) is what disables the traction control system or the vehicle stability enhancement system.
The code means the EBCM is receiving faulty data from other modules or is faulty itself.
C0161 code:
C0161 Possible Causes What does this mean? Faulty ABS/TCS Brake Switch (Stop Lamp Switch) ABS/TCS Brake Switch harness is open or shorted ABS/TCS Brake Switch circuit poor electrical connection
How do I fix code C0161? Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
Possible Symptoms Anti-Lock Brake System (ABS) Warning Light ON Engine Light ON (or Service Engine Soon Warning Light)
C0161 Description The Stop lamp Switch is a normally open switch, when the brake pedal is depressed the Electronic Brake Control Module (EBCM) will sense battery voltage. This allows the EBCM to determine the state of the brake lamps.
In other words, this is going to require some diagnostic time by someone who knows what they are doing.
Other members here that have dealt with this before will likely chime in. Give them some time to do so.