2002 Columbia air leak behind dash. Need help.

I've yet to come across something that you're looking for. My best advise is to simply take a picture of what you're working with and maybe some peeps here can help you identify things. If it has anything to do with the MV3 valve (red and yellow knobs) I believe that the bendix website has a manual that'll identify what ports do what. As a last resort you may have to spend an day figuring out things by trial and error.

 

Also, if you know the model# of the component you're looking at you can download a manual from the Bendix site I believe. I think most of the air components are handled by them. This is what I did when I was trying to figure out some air issues I was having a while back.

Lastly, if it's your mv3 valve making the noise be careful since the hiss may be indicating a leak elsewhere, like a faulty trailer check valve or something.

 

You're just needing the routing for the dash? Got a VIN? I can't do the last 6 because Freightliner has changed their system do to copy cat of VINs with the new trucks this year. Either the VIN or the year and I will see what I might have for you.

 

I had a 2002 Century. 1st leak was a valve in-front of the shifter, about 8 inches above the floor. You take the plastic cover off the dash and its right there. takes maybe 10 minutes to replace. I can't remember what it did, I just recall how freaked out I was and how simple it was to fix. The other leak was the break-valve. Did that myself. Unscrew the dash panel, dis-connect the valve and hoses, replace.