Some 2018-2023 Equinox and Terrain models may have DTC C0561 43 (System Disabled Information Stored – EEPROM Incorrect Programming) set and the park brake will not learn after rear brake service has been performed. DTC C0561 43 indicates that the park brake actuators position is unknown. A Service Park Brake message also may be displayed on the Driver Information Center.
These conditions may occur if the first steps in the rear brake service instructions are not followed. Refer to the Rear Disc Brake Pads Replacement procedure in the appropriate Service Information to ensure that all service procedures are being completed properly.
The service procedure instructs to check the fluid level in the brake master cylinder reservoir. (Fig. 13) The brake fluid level in the master cylinder reservoir must be at 1/2 or lower between the maximum/full point and the minimum level to allow sufficient space for the fluid to return to the reservoir when the rear caliper retract is commanded. If the fluid level is higher than 1/2, brake fluid should be removed before continuing with repairs.
Fig. 13
The caliper will retract when commanded but will stop when the reservoir is full. If there is too much fluid in the reservoir, the piston will not be fully retracted into the caliper. (Fig. 14)
If this occurs and then the piston is manually pressed in the rest of the way so that the caliper can be reinstalled, the excess fluid pressure will damage the pressure sensor(s) in the Electronic Brake Control Module (EBCM).
Fig. 14
Typically, the park brake data for one or both of the pressure sensors will show the default value of 14,400 NM. If a pressure sensor(s) is damaged, it will be necessary to replace the EBCM. Due to the nature of this damage, EBCM replacement is not a warrantable repair.
For more information, refer to #PIT5953.
– Thanks to Ken Cole
As long as a clamp wasn’t used on the piston and no other damage has occurred, the piston should retract until seated or it deadheads against the cap again.
if you lower the fluid level after it stops will the pistons continue to retract if commanded again?
is this the best way to service any and all vehicles with electric parking brakes so as not to damage the ebcm?
How about a M/C cap with a one way check valve / weep hole to allow fluid to escape , rather than destroying the E.B.C.M.
The first step in the rear brake service instructions is to lower the fluid level in the reservoir to half full to make room for the fluid to return to the reservoir when the pistons are retracted. As covered in #PIT5953, if the instructions are followed, there is not an issue. As there is not a position sensor for the actuator, the pressure sensors identify if the caliper is clamping the rotor or is fully retracted by monitoring for the pressure rise when these occur.
So essentially you are saying if a lube tech “tops off” the brake fluid, or a brake flush is done as maintenance, The reservoir could junk the EBCM. And the customer is unknowingly on the hook for a new one, because someone else messed up. This seems like a ridiculous waste of technology. Why are we measuring pressures on that side anyway? So if the parking brake is applied, then the reservoir is filled, the parking brake won’t release? Why don’t we just put a tamper proof cap on the M/C reservoir?