BSR Music

99 E320. PSE pump under backseat is making noises. humming , pumping after start up. Is this normal? Should I be concerned? All locks and windows work perfectly.. Although I did notice the cruise shut off a few times the other day

Plutoe

The PSE is not on the same circuit as cruise control, typically if you loose cruise control I would look to the break light switch as a potential issue.

My PSE does not hum and like yours works fine!!

Musikmann

Could the hum be your fuel pump? That's the only noise like that I can hear and that is normal.

BSR Music

it's definitely the pse pump. ( enclosed by foam under the seat. )
touched it while it was making the noise. so verified.
All lines are attached well. Just curious if it was normal... All locks are working fine.. not sure what all this pump runs to though. Still learning all I can about 1st MB.

Did notice the battery was wet, and in the batt compartment was wet on bottom as well. Little concerned about this because the fuse box & pse pump are located here too. If its battery acid or fluids, would hate for it to damage any of these. (Keeping a eye on it.)

ALSO - does this pse have anything to do with stiff riding in rear? such as hard bounce over bumps (air ride or such?)

Plutoe

Nope, the PSE is the control unit for the central locking system. Stiff rides, I would look to your suspension system. Another hint would be to read your owners manual!!

BSR Music

Plutoe.. I do my homework before I post new threads so..The manual has been read back to front and sideways. Not seeing anything specific.
Of course... since they dont want you to work on your own vehicle, this is where the MB service comes in to jack up those $$ on parts labor - Unlike any other vehicle, MB has alot of features that I am slowly learning about thanks to people like you & in the forum. Unlike some out there, I'm not afraid to get dirty to fix my own car, and all I learn here is appreciated.

Musikmann

I would try to find the source of water in the battery area. As you noted, there is a fuse box there and if gotten wet that can cause all sorts of weird electrical things.