OK, I get a call tonight from a friend of mine who tells me his elderly aunt is stuck in a parking lot with the car going nuts and she's afraid to drive it anywhere. I took a rid over there and here's what I found.

Sitting in the car with the engine idling:

The door locks pop up... 5 seconds later the go down and repeat up... down... up... down, every 5 seconds.

The sun roof - at random, opens itself up...

The trunk - at random, pops open...

Also, not sure if it's related but there's a button on the dash with a little picture of a tow truck/car. It has a little red light on it that doesn't go out if I press the button. Now, here's the strange thing: If I hold this button down, all the chaos stops. The second I release the button, everything resumes going nuts.

One other interesting thing is that the trunk lid doesn't open on it's own when you're actually under way, driving down the road.

So, besides a poltergeist, I'm stumped. Any ideas?

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

My first thought...stick a voltmeter on the battery; if it's overcharging these kind of things are pretty common. Overcharging = bad voltage regulator, pretty easy to change (and a weak link in these cars anyway).

All these things are on the CAN bus (yes, Oldtimers, MB's went digital in the late 90s). You can try to reset it by disconnecting the battery for about 2 minutes, but make sure you have your radio code 1st.
One of the 9-10 devices on the bus is acting up and triggering faults elsewhere. The PSE pump is a major one, and it sits behind the battery under jute padding underneath the rear seat. Check that it is not wet, because there's a circuit board in its base.

__________________
Prost!

OK, thanks for the quick reply. I have software on my computer that interrogates all of the CAN bus devices and it reports no errors.

Oh, I will also add that the alarm was also going off randomly, it was cold and raining when all of this was happening in a strip mall parking lot!

The car is inside a garage now and we disconnected the battery to avoid any more craziness. While under the seat, I unwrapped the door lock pump (PSE pump?) from it's padding and noted that it felt wet. Now, granted, everything felt wet at the time but I did feel cold wetness when I picked it up. Since it was dark, I couldn't really tell much about it.

I'll have to look again in the light.

I'll also check the voltage output with the car running.

Thanks again, will keep this up to date.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

As noted, most likely an interior CAN issue.

Possibly water in the connector, PSE (central locking pump is a good bet.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
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Retired Moderator

Thought I'd post a follow up to this situation. We checked thoroughly and found nothing else unusual. However, the lady recalled having a full bottle of water spill into the back seat.

This combined with my perception of wetness in the padding leads me to believe this was causing the problems. Inspection of the pump shows no evidence of water damage but since this was pure bottled water, I don't expect to see much.

I had removed the back seat to disconnect the battery and left the area open over night and I believe this dried up the water sufficiently to cause the problem to go away.

Thanks again!

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Evan, too bad the lady didn't mention the full bottle of water spilling in the back seat when the car's erratic behavior started. There is always more to the story than most people share during a "crisis". I'll add this incident to my memory bank.

__________________
Fred Hoelzle

OK, another update: The car has been in the garage for a couple weeks now with the battery disconnected. The battery was re-connected and within a day, the windows had run themselves down. (Car still sitting in the garage, never started nor the key placed in the ignition.)

Next step, the windows were run up via the remote and again, within a day, they were back down. Again, key was never placed in the ignition.

Our next move is going to be to disconnect the vacuum pump for the door locks, then each front door computer in turn.

I'm also going to run another scan of the processors and see if anything unusual shows up. On that note, does anyone know the actual name for each of the body processors? I have a big list on my program and I'd like to narrow it down so I'm not testing every system on the car. If I get a chance, I'll try to post the list but it's not easy since the choices are on a drop down window.

Lastly, there is the persistent red light on the "tow truck" button. What is the function of this button and what does the red light mean? No matter what is done, the red light is always present.

Thanks for your thoughts.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

The tow button is to disable the tow away alarm when the car is parked on a ferry, train etc or other surface that may move. When the system is turned on the alarm will trigger when the front end is raised.

__________________
1989 300CE

So, here is what I hope to be a final resolution to this issue.

I polled every system on the car and came up with nothing definitive that would point to any particular problem. The car has been sitting in the garage with the back seat out since the day of the first post and everything is nice and dry now and the systems are behaving properly with the battery connected.

The only remaining mystery is the persistent red light on the tow button. I pulled the door lock pump from under the seat and began pulling the connectors off. Amazingly, the red light went out! I continued to remove the rest of the connectors and that's when I spotted the badly corroded pins on the two multi-pin white and black connectors on the end of the unit.

I removed the vacuum lines and pulled apart the pump and this is what I found:





(Sorry for the one crappy picture)

I don't think that happened all at one time but I believe that the combination of the spilled bottle of water and the cold rain aggravated situation to the point that things started acting up.

We plan on getting circuit cleaner and a toothbrush and cleaning it up to see if it solves the problem permanently.

Attached Thumbnails

     

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

If it was my car, and not a "customers", I would hit that board with brake cleaner then a dab of contact cleaner/lube and reassemble.

Goodluck

__________________
08 R320 CDI current

Past
95 E420
87 300D Turbo 5spd
90 300TE
83 300SD
85 300TD
92 400E
85 190D

Did ever get the problem completely resolved? I have the same exact issue with my car, have replaced the PSE with a used known good one and still experiencing the problem. All windows roll down and the moonroof opens itself.

Anyone see an MB tech service bulletin on this ???

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

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