Parking brake intermittently doesn't release

[WilboVIBC]

I'm in a 2007 IC FE bus and my service brake is intermittently refusing to release. Yesterday I drove it all day, applying and releasing it... And when I went to release it to move it to our camping spot, no dice. We slept there, and in the morning or released just fine.

Nothing wrong with air system, builds and holds pressure fine.

I noticed an electrical component going into one of the lines... I was curious if it was a shut off celinoid for when the bus is not running... Or something along those lines. Just curious if that is faulty. I'm no mechanic, so am just guessing.

[WilboVIBC]

I just wanted to update this thread... I think my issues stem from not understand the parking brake interlock system. The front door set to open my prevent the parking brake from working. I'm going to start looking into removing these components and am looking to this thread for a start.

https://www.skoolie.net/forums/f37/p...out-26675.html

[Booyah45828]

Sorry nobody responded.

Lets get terms correct first. Your parking brake is actuated by spring pressure inside the brake chambers, and released by air pressure from the yellow handled valve. Your service brakes are actuated by air pressure which is provided by the brake pedal treedle valve. Parking and service brakes are two separate things.

It sounds like your issue is with the parking brake, and it not releasing intermittently, versus the service brakes.

From reading that other thread, you've likely learned that your parking/spring brake release can be disabled through different safety interlocks present on the bus. Those interlocks can be controlled by switches on doors, windows, and hatches.

Whenever I see someone complaining on here about parking brakes not releasing, almost 100% of the time it stems from a handicap door, and someone clipping the wrong wire when removing the lift. Have you done any wire tidying or lift removal recently? If not, has the lift door been jiggled or opened in correlation with the parking brake not releasing?

[WilboVIBC]

Thanks for responding. I've taken my 20 hr airbrakes course... and I still screwed up the terminology. Gosh!

I've had a whole host of other electrical issues, so I think there might be some electrical gremlins in there that effect the interlock. I have not done any wire cleaning... although I did take out the lift, and disconnect the hatches and emergency windows.

I'm having an international repair shop look at it because I'm so over my head with troubleshooting the electrical issues. Maybe I'll create a write up after the diagnose things for me.

[WilboVIBC]

This ended up being a back lift door interlock that is overly sensitive to door latch position. I double-check it before starting the buss each time. Haven't had an issue since I noticed the connection. Need to figure out how to bypass the system.

I also bypassed the interlock for the emergency windows and doors with this video, which saved us on a 7,000 km road trip (employed it 2 hours before we left on the trip).

https://www.youtube.com/watch?v=6cU9boOTJS0