I saw in a prior thread that you can reset your auto door closing functions by disconnectin the battery for 15 minutes or pull a fuse. My question is where is the battery located and if I disconnet my battery will I have to take it to the dealer to get reprogrammed? Should I try this to attempt to fix this problem? My trunk auto closing is working fine.

Tks Ron

 

there was a previous thread that helped me just 1-2 weeks ago. I did not disconnect the battery, just went to the trunk, on the right hand side of the trunk wall there is a small door that is a fuse pannel. You can read the descriptions, but I think it is 19 and I just removed it for a few minutes/seconds. I am not sure I even had to turn on or off the car, just pulled out the fuse, and then reinserted it, and presto, my soft close started working as well as the trunk then closed by itself. The thread suggested finding out why you needed to reset it first, but I went right to the solution, not knowing how to do much else.

below is the long thread, and worst case, because I am not up to this!!

Getting to know your Closing Assist Pump: Function, Tips, and Fixes
An article written and kindly provided by Brett Allison (Updated 12/27/07)
I. Introduction
If you’re reading this, you must be having problems with your closing assist system. Probably it doesn’t work at all. You may have experienced the slow door by door failure that many seem to report. One door stops working. Then over the course of a week or so, all the doors and the trunk stop working one by one until eventually nothing works. Before you let a less knowledgeable person convince you that you need a new pump (about $400 right now), allow me to see if I can convince you otherwise.
Before I say more, one of the best things I did was get a subscription to alldatadiy.com for my car (see bottom of article for a link). It’s a very well-spent $24.95 for the first year and $14.95 per year thereafter. Alternatively, you can purchase a W140 manual CD-ROM from various sources for $150-$200. I have both, and I have found that alldata has had everything that I’ve looked at on the CD so far.
I bought my W140 (1997 model S600 sedan) knowing that the closing assist system was not functioning. Some posts on this board got me started in the right direction, but I learned more than I expected as I dug into the problems with my system. I’ve been able to breathe new life into my pump and return my system to 100% reliable operation for almost a year so far. This document compiles my expertise gained from troubleshooting my own system and from helping a couple others on the board do the same over the last few months.
There are two air pumps onboard your W140, the pneumatic system equipment (PSE) pump (also referred to as the central locking pump) and the closing assist pump. The PSE pump performs several functions including locking/unlocking of doors, inflation of lumbar support bladders, operation of reverse antennae on the earlier cars, extension and retraction of the trunk handle, release of the trunk striker eye for auto-closing, and providing vacuum to the vacuum reservoir when the car is not running. This pump is located under the rear seat on the passenger side. The closing assist pump is involved only with the auto-close function of the doors and trunk lid. It is located in the trunk.
II. Accessing the Closing Assist Pump
The closing assist pump is simply crammed into a foam cube tucked between the left rear fender well and the gas tank. You must remove the trunk liner on the left side, and it helps a lot to remove the liner piece at the forward wall of the trunk. It is possible to just bend the corner down to get the pump out, but access is much easier if you remove the whole liner. It only takes removal of a few more of the plastic push rivets. If you have a CD player, you must remove this first in order to remove the left side liner. It’s easy: 2 screws and one electrical connector. If you don’t see the pump at first, follow the bundle of red plastic air lines.

Just pull the pump out. The lines are labeled with initials which, I believe, are short for German. VR = vor rechts = front right door. HR = hinter rechts = rear right door. VL = vor links = front left door. HL = hinter links = rear left door. HD = not sure = trunk. SK = not sure of this one either = pump outlet line, hooked up to nothing.

I understand that for coupe models, the pump is identical, but the rear door lines are simply not used. One boarder (jvallet) stated that it should be possible to use the rear door outputs if one of your front door lines becomes unusable by simply plugging the appropriate door line into the rear door output and then rewiring the connector so the micro switch sends the proper signal to the pump to activate the rear door output. I cannot comment further.
III. Pump Function
Understanding how the pump functions is central to identifying any problems with your system. The heart of the pump is a sizeable electric motor that directly drives the air pump. What is neat about the design is that the pump can both pull a vacuum or develop pressure on any of the door or trunk lines independently and at the same time. That way only the door or doors that need it get pulled closed. This is accomplished by electric solenoids that switch each line between pressure and vacuum. The solenoids are controlled by the pump electronics which receive signals from micro switches in the door latches and trunk latch telling the pump that a door has partially closed and needs to be pulled shut.
The pump does the closing of the doors and trunk with pressure. It pressurizes the lines causing the extension of pistons in actuators, which in turn move levers in the various latches, which pull the doors or trunk closed. The pump runs until one of two things happens: 1. It reaches a pre-set shut-off pressure (at which point the pump "thinks" it has properly done its job of closing the door or trunk), or 2. It never reaches its pre-set shut-off pressure and then runs for a set amount of time and turns off (that is, it "times out"). After pressurizing the line and doing the auto-closing, the pump then pulls a vacuum on the line, presumably to ensure retraction of the actuator piston. The pistons are spring loaded, but I suppose occasionally, they may not retract fully when the pump releases pressure.
Case 2 is where a lot of problems arise. If the pump times out twice on the same door or trunk line, the pump electronics permanently turn off function for that line. That’s just the way the system is programmed, and it’s usually why just one door stops working. The pump specifically turned off that line because it timed out twice. Back to why the pump timed out… because it couldn’t reach the pre-set shut-off pressure. Why couldn’t it reach its pre-set shut-off pressure? Two reasons: 1. Because an air leak has prevented build up of enough pressure or 2. Because the shut-off pressure is set too high. So the course of action is clear. If you don’t have an obvious air leak, you’ll want to address the shut-off pressure. The pump has a pressure sensing shut-off switch which is adjustable. The following troubleshooting section will show you how to reduce the shut-off pressure on your pump thereby preventing the pump from timing out and shutting down on its own.
This very simple adjustment completely restored reliable function to my system. Hopefully, it can for yours, too, but there are many other failure possibilities, which I’ll discuss in the next section.
IV. Troubleshooting Your System
(Modified note 9/3/06) Note: Be careful when removing the air lines from the pump. I used a screwdriver to pry them off and had no problems, but I know that others have broken off the nozzles, which may force you to buy a new pump. Make sure you pry against the hose end, and not the barb on the outlet. I have found the factory recommended method is to use the fork of a 7 mm wrench as a pry tool so that you get prying force distributed equally on either side of the air line connector. Note that the 7mm wrench trick is for the "male" style hose ends. Also - the contactor on the newer style pumps doesn't shut the pump down immediately on contact. There's a delay before the pump shuts down. Keep this in mind when testing.
a. Bringing Your Pump Back to Life
There are two reasons why a door may fail to close. Either your pump is not working, or your pump is not getting a signal telling it that a door has partially closed, i.e. the micro-switch is bad or out of adjustment, or the wiring from the switch to the pump is bad. Most likely, it’s the pump that has shut down. First thing to do is to try pulling fuse 9 in the trunk fuse box. Pull it out, wait several seconds and replace it. This fuse is labeled for the closing assist pump. Try a door or the trunk to see if the pump turns on. Some have reported this works to bring their pumps back to life, but this never worked for me. At this point, pull out the pump as shown above, and remove the electrical connector on the pump, and replace it. Completely cutting power to the pump resets the electronics so that it will again operate all lines until the two-time-out thing starts happening again. If you do nothing else, your pump may work for a while, but it will again eventually shut down because of the same reasons that caused it to time out in the first place.
If your pump comes back to life, congratulations. You very likely don’t need a new pump. If it doesn’t, I probably can’t help you. Perhaps the electric motor has shorted out. It works hard and gets hot very fast inside the pump housing. Or maybe the brushes have simply worn out. It may be possible to replace the brushes, but I don’t know. If you’re electronically inclined, maybe you can tackle the problem. There is also a printed circuit board inside the pump. Plenty of components can fail there, but I cannot address this.
If you have a door that works intermittently (sometimes a door works and sometimes it doesn’t, seemingly at random), your problem may be a micro switch issue. Sometimes the micro switch gets tripped and sometimes it doesn’t when you close the door. Intermittent function is never a pump issue. Once the pump shuts down a line, it’s off for good (until you completely electrically disconnect it by pulling the connector).
Once you have the pump on your trunk floor, you can observe the two-time-out-then-shut-down behavior of the pump. Disconnect the trunk line (HD), and leave the nozzle open. Now, simulate the closing of the trunk by operating the catch in the lower trunk latch with your thumb. The trunk lights will turn off, the trunk handle will retract, and the HD line will hiss loudly with air pressure from the pump. The pump will run for around 10 seconds and then stop. All seems well. Do it again. All seems well. Do it a third time, and nothing will happen with the pump any longer. Unplug the electrical connector and plug it back in. Simulate trunk closing again. All back to normal.
Now, check your pressure shut-off mechanism. Put your thumb firmly over the HD nozzle preventing any leaking, and then simulate trunk closing. The pump will start up, and it should shut off almost immediately. That is because it pressurized the trunk line, and with your thumb over the nozzle, it reached the shut-off pressure very quickly and turned off. You can repeat this indefinitely. As long as the pump reaches its shut-off pressure and doesn’t time out, it operates just fine. If your pump doesn’t shut off when you do this, you’ve got a more serious problem with the pressure shut-off switch.
b. OK, My pump works. Now what?
Leak checking is next. As mentioned earlier, air leaks will cause the pump to time out because a leak may prevent reaching the shut-off pressure. There are a couple of ways to find leaks. You can use a pressure device with a gauge (Mity-Vac or similar) to pressurize the line in question and watch for leak down. There are specific Mercedes factory specs for leak down. I don’t know what they are, but it is on alldata. Alternatively, you can simply operate the door or trunk once you’ve reactivated the pump and listen carefully for the telltale hiss of a leak. The pump really moves a lot of air. I believe that any leak large enough to prevent the pump from reaching the shut-off pressure will be audible. Just listen.
There are myriad opportunities for leaks. Lines can separate inexplicably from connectors. Lines can get pinched and crack. Lines can get chaffed and worn through. The actuators are also a source of leaks. These have rubber o-ring seals that can get hard and crack with age. There may also be leaks internally inside the pump. These may be fixable or maybe not. More on this later.
One boarder (beelootin) contacted me recently when his trunk stopped working followed by everything else. After he found his pump was fine, his mechanic turned down his pump’s shut-off pressure per my instructions and also found the trunk line had a leak in it. Apparently the line was routed poorly and was rubbing somewhere every time the trunk opened and closed. They cut out the holed bit of line, rejoined it with a good seal, and his system is now working fine.
c. I’ve rejuvenated my pump by electrically disconnecting then reconnecting it, and I’ve confirmed that there are no major leaks. Now what?
It’s time to evaluate your pump’s pre-set shut-off pressure. You can use any door or the trunk. Partially close the door/trunk, and carefully watch the closing action. You’ll hear an audible click when the latch catches, but then the door/trunk will be pulled shut for a period of time after the click of the latch. Finally, the pump will turn off and the door/trunk will relax to its normal fully closed position. First, time how long it takes for the door to audibly latch. This should be about 1-1.5 seconds. If it takes longer to latch the door, your pump is not providing enough pressure. Why? Leaks, or maybe a worn out pump head, or something else (??). If you can’t find a leak, then I probably can’t help you further.
Now, time how long the pump runs after the door or trunk has audibly latched (that is, how long it keeps the door “sucked” closed after it latches). I found my pump ran for almost 10 seconds after the latch had clicked, needing extra time to build up enough pressure to trip the automatic shut-off. This extra pumping time is unnecessary. If your pump takes more than 7-8 seconds to shut off, then you’re a candidate for adjusting the shut-off pressure.
The pump only needs to run as long as it takes to latch the door. The risk of your pump running for too long is that every once in a while, before it reaches its shut-off pressure, it instead reaches the time-out time and charges a time-out to that line. After one more of these, that line is dead. The pressure shut-off is a balancing act. You want to set the shut-off pressure high enough so that enough pressure is developed to latch the door or trunk, but you don't want it set too high so that the pump takes too long to reach the set pressure and times out.
d. Adjusting the shut-off pressure
Pull out the pump and disconnect all the lines. Label them before disconnection if they aren't already. Unscrew 6 screws on the top of the pump, and pry off the cover.

Admire the dual manifold design with solenoid switching between pressure and vacuum for each door and trunk line. Kinda cool. The pressure shut-off diaphragm is visible in this pic.

OK, here's the business end. Notice the dual contact switch that is operated by the white piston from the pressure sensing diaphragm. That white piston has a screw in the end of it which can be adjusted to adjust the shut-off pressure. If you screw it out a bit, then the piston will have to move less to trip the switch; therefore, the pump will shut off at a lower threshold pressure.

Just turn the screw to adjust it. I just used needle nosed pliers. Finally, here's my original vs. new setting.

Now, your pump will shut down automatically in a lot less time after closing the doors and trunk. You can play with the adjustment a bit so that the pump run time is to your liking. I’d say 3-4 seconds after the latch closes is all that is needed, and you could probably set it for less than that. My closing assist system has run with 100% reliability for almost a year now, after performing the shut-off pressure adjustment. The obvious fringe benefit of this adjustment is that the pump runs for a much shorter time each time it closes a door, so it should also extend the life of the pump’s motor.
e. A case of a bad pressure shut-off diaphragm
This finding convinced me that most closing-assist system failures that W140 owners experience may well be caused by either maladjustment or failure of the pressure shut-off mechanism.
A boarder (posix) posted that his pump had quit running. I responded insisting that he adjust his shut-off pressure. When he dug into his pump, he found that the problem was not that the shut-off pressure was set too high, but that the white piston of the shut-off switch mechanism wasn’t moving at all. So his pump was timing out every time it operated. The piston had cocked to one side and bound in the black case becoming stuck (see pics above). He went farther than I ever had and disassembled the diaphragm (the black housing that the white piston moves in) eventually finding the root cause of the sticking piston. It turned out that the rubber diaphragm that pushes the white piston had developed a tear. The tear was on one side of the diaphragm such that as the pump pressurized, the diaphragm would push one side of the piston only causing the piston to **** sideways in the black housing. Since the pump develops quite a bit of pressure, the piston would get wedged in place tightly once it got started crookedly and become permanently stuck. Posix was able to take apart the diaphragm assembly and use the tip of a latex glove finger to re-seal the diaphragm and make it air tight again. Very ingenious, indeed. He said everything was back to normal, and he had also adjusted his shut-off pressure appropriately in the process.
Here’s a pic from Posix’ post showing the 3 screws (green) and the 3 solder connections (cyan) that need to be removed to take the pressure shut-off diaphragm off the circuit board for disassembly.

f. The newer pumps with a different shut-off mechanism design and a technique for fixing leaks from damaged nozzles.
Another boarder (jvallet) posted that his S500 coupe was having driver’s door problems once again after pump replacement for the same problem 3 years ago. Jvallet found the door would work for a very short period, then stop permanently until he disconnected his battery. Then it would work again for a short time. Disconnecting the battery was serving the same purpose as removing the connector from the pump. When he pulled out his newer style pump and listened while it operated the driver’s door, there was an obvious hissing sound from a leak. He wiggled the air line connector on the output nozzle and found the noise changed. He found he could adjust the connector and minimize the leak enough to get the door to close, but the pump would run for 7-8 seconds before it reached the shut-off pressure. Although the leak was reduced, it was still audible. When he removed the air line, he found that the nozzle had a small chip broken out of it that appeared to be causing the leak. Jvallet wrapped the nozzle in what he described as water pipe sealant (I think Teflon tape) and then replaced the air line connector. When he tried the driver’s door again, it operated just fine, and the pump shut off automatically in about 2 seconds after the door latched. Problem solved. There were no more sounds of a leak.
Jvallet kindly provided this pic of the newer style pump. I have circled the output nozzles with chips in them. He reported the nozzles were particularly fragile, and he actually caused one of the chips when he was placing the cover back on the pump. On the right of the pump is the new design of the pressure shut-off mechanism. There is still a screw to adjust the shut-off pressure, but in this case, the screw is the actual electrical contact that turns the pump off.

g. Severe air leaks from loose bolts at the pump head.
A poster (SEXYREX) recently related his experiences with fixing a major leak inside his pump. Every time he reset the pump by pulling the fuse, he would get two operations then nothing from each line. Even firmly blocking an output line with a finger, did not cause the build up of enough pressure to trip the shut-off switch. Clearly, there was a major leak central to the pump since every line was affected equally, or there was a problem with the pressure shut-off switch causing timing out. After some inspection, he noticed dust patterns indicating air escaping from the seam in the pump head. It turned out that the screws holding the pump head together were loose. A quick tightening of the screws completely restored function. Now, when firmly blocking an outlet nozzle, the pressure shut-off switch turns the pump off immediately as it should. After adjusting the shut-off pressure, all doors operate normally, and the pump turns off about 3 seconds after latching.
(1995 pump shown)
h. A case of a plugged line to the pressure shut-off switch diaphragm in the newer style pump.

 

hi seem my s430s automatic assist always acts goofy after i travel. Specially high altittude places thinks its the pressure idk. Taking off the neg ground always resets this problem and is also a good way to reset check engine light! u might get a asb warning lite that comes on but will dissapear within a minut of driving!!!

 

I am embarrased, I can not locate the battery in the trunk in my 2004 S430. I took out the spare tire and started pulling off the fabric trim that I stopped. Please help.

 

your battery is on the far right side of the trunk the small floor panel pops up. its not where the tire is but more to the right of the trunk. there is a fuse box under the rear seat....where the floor light is.....pop off the cover and youll see the fuse box with relays and fuses. im not sure off hand which fuse it is but it is a small 20 amp fuse. you should have a a fuse chart where your spare tire kit is located and look for central locking or closing assist.

 

chassis221 -- I located the fuse 20 AMP under the back seat passenger side pulled the fuse stated the car and put the fuse back in and the auto close feature is working again !!!!! I can not thank you enough. !!!!! Ron McDermott 2004 S430

 

your welcome, glad i could help.