i just got my car back from having the tranny controller worked on, as well as the seat sensor in the passenger seat that was causing a SRS light to flash on the dash. anyway, got the car back with no problems or so i thought. that night, i was trying to pop the trunk and it hesitated -then opened. no problems for the rest of the night. then i did not drive the car for 4 days. today when i tried to get in the car, it would not unlock. i had to put the windows down with the remote, and then manually unlock it. i tried operating the locks from in the car and from the remote. still nothing for about 15 minutes. tried different remote/keys, and tried the lock/unlock button from in the car. nothing. i read on the forum that there is a pump that controls the locks and the lumbar for the seats. sure enough, the lumbar was not working either. so i read on here that the pump is under the back seat, but i could not get the seat to come up and i did not want to break it.

so anyway, what do i do now? i am figuring i will wait and see if it happens again and then take it to an independednt benz mechanic around here -unless of course, someone can point me in the right direction towards an explanation/solution. please help if you can!

 

This is directed to the 140, but all are wery similar. At the base of the rear seat there are latches that will relase the seat, it pivots from the front upwards. I would then slide it forward to disconnect the seat heater wire (if you got them) you should be able to remove the seat bottom from the car. The pump is located in a foam enclosure and should have multy colored hoses and three wiring looms. This pump runs forward and backward to produce either vacuum or pressure, pressure to unlock and vacuum to lock, and runs untill it gets a electrical signal from the sensor on the front door actuator, or it hits the timeout paramater and shuts off. The pump is also enabled by (2) microswitches the locks and trunk. The door, trunk, gas lid, are all tied together so a leak in any of the linescan effect the operation. There asr ports for back up rods, and rear vacuum headrests(if you got them). The pump also runs when your lumbar needs pressure, or your HVAC needs vacuum for the controls and the engine is not producing any or off these are stord in seperate reservoirs
I would check fuses by pulling them to see if the pump can be reset, and then chase the problem with a tool called Mighty Vac to check for leaks

 

I have a 2002 S430 & had problems with the trunk closer assist not working. It turned out to be a split in the air passage to the closer in the trunk. The opener worked but the closed did not. After installing a replacement it still did not work. A friend told me to find the fuse and replace it. I did not find the fuse, but did unhook the ground cable for 5 minutes then hooked it up. It has worked since then (about 3 months). You may be able to rest the pump this way.