Last week on an 05 International CE, we weren't able to release the parking brake. We cut the short cable and brought it back to the shop. Short cable seized into the SAHR so we replaced both cables, park brake pads and the SAHR canister. When we got around to the diagnostics on the initial problem, the only code we pulled was "Unable to release parking brake." Checked wiring to the parking brake supply valve and I verified power with a headlamp to make sure I had enough amperage to operate the coil. Everything looked good so I installed a new park brake supply valve and bled the system. Still had the same issue. After convincing myself it was something in the the HCU not allowing pressure to pass through to the SAHR, we replaced the HCU and still have the exact same problem. Not sure where to go here. Am I missing something??? What else is needed in the system to release the parking brake? Any ideas would be greatly appreciated.
is the system seeing the foot brake applied to release the park brake?
According to the Toolbox program, yes it is receiving the signal. It's also seeing the signal from the park brake switch as far as being centered, applied or released.
You said you replaced the HCU did it come with the ECU ? and did you program the ECU ? Another thing look at the travel switch position as it relates to the park brake , also can you release the brake with the laptop ?
Meritor Wabco parking brake help needed
Posted - 11/16/2017 : 04:10:42 AM
