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  #1  
Old 11-05-2006, 10:10 PM
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Location: Western North carolina
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Door locks, window motors, roll bar failure?

My 91 300SL has 97000 miles. I just had to have the drivers door lock assembly replaced. I was told that my keyless entry wasn't working because of a bad vacuum pump. I was ready to order one for about $375 when my passenger side window quit working. Then the roll bar wouldn't lower and finally, the driver's window won't go down. Does anyone have an idea what might be causing the problem (s)? Fuses look fine. Thanks for any help.

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  #2  
Old 11-07-2006, 12:35 AM
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Location: Milwaukee Wisconsin
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You've checked the fuses in the trunk? There are two fuses: 16 amp. One for each window. The window switches in the console have been known to fail. With the engine off, but the key on, can you hear the relays click under the right rear storage compartment? The windows are activated by relays in the soft top controller under the storage compartment. If the relays click, the switches are OK. Have you pulled the error codes from the soft top and roll bar controllers? Has the car been up on a rack recently? That can set off the roll over switches on the axles and cause problems. Use the forum search function for additional info.

Mercedes Soft Top Controller Reset Procedure. R129 1990 thru 1994.

Locate the diagnostic connector: Under the plastic cover near the hood-up switch on
the passenger side of vehicle near the strut mount.

To recover codes for the soft top controller:

Connect a normally open (N.O. S.P.) switch between pin 1 and pin 10. A simple push button switch with leads or a short jumper lead will also work OK.

Short (close switch) 2 to 4 seconds to read error codes.
The lamp in the red top switch ( in the console ) will flash out a number of pulses.
Count the pulses and refer to the error list below.

To clear / erase a code: Short (close switch) for 6 to 8 seconds.

There may be multiple codes stored.

Some codes may require reading / erasing twice before they will clear.

The codes that will suspend operation of a soft top on the R129 are 21, 22, 26, and 30.

A code of "1" indicates no faults and no hard top in place, while a code of "20" indicates no faults and the hard top is assumed to be on the car.

3.= Limit switch, right locked ,soft top storage compartment cover.
4 = left compartment cover closed switch
5 = right compartment cover closed switch
6.= left front latch switch.

10.= left rear latch switch.
11.= right front latch switch.

16 = roll bar retracted switch.
17 = Left window failed to lower (limit switch open).
18.= Right window failed to lower (limit switch open).

20 = Hard top installed, no faults.

23 = roll bar control unit not functioning.

25.= contradicting inputs.

27 = insufficient voltage.
28.= Speedometer signal is missing.
29.= Wheel speed from ABS control module missing.
30 = Top operation disabled (due to #29).



Roll Bar Codes and Reset Procedure.

Connect a 1K ohm resistor in series with an LED (+) anode to pin 16 (+12V) and the LED cathode (–) to pin 7. To recover: Short pin 7 to pin 1 ( ground ) with a push button switch.

Code 1 = No faults in system.
Code 2 = Roll Bar Control Unit
Code 3 = Voltage Supply
Code 4 = Driver Seat Belt Lock Relay (K18/2) open or short circuit to terminal 30 and/or 31
Code 5 = Passenger Seat Belt Lock Relay (K18/3) open or short circuit to terminal 30 and/or 31
Code 6 = Roll Bar Deployment Solenoid (Y57/1) open or short circuit to terminal 30 and/or 31
Code 7 = Left and/or right rear axle switch open or short circuit to terminal 30 and/or 31
Code 8 = Roll Bar Warning Lamp
Code 9 = Roll Bar Warning Lamp and/or impulse counter held too long to erase malfunctions
Code 10 = SRS Control Unit
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  #3  
Old 11-07-2006, 07:24 AM
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Join Date: May 2001
Location: Las Vegas, Atlanta
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That is outstanding of you Tecqboy to post that info. Regarding the LED you mentioned, I would recommend Radio Shack's part 276-209. I like this particular one because you don't need the 1K-ohm resistor.
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Old 11-07-2006, 12:24 PM
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Location: Milwaukee Wisconsin
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Thanks Bob. I'm sure that my list is not complete, but it's what I've put together seaching the forums. I experienced a complete controller lock-up after a new set of tires. ( Don't know what they did besides drop the axles.) Without this forum, I'd have had to go to a dealer and probably pay a huge sum for what is really a simple fix when you have decent information.
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  #5  
Old 11-07-2006, 01:50 PM
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Location: Western North carolina
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I appreciate both of your responses and excellent advice more than I can tell you. I did find some bad fuses in the trunk. Replacing them restored the passenger window, roll bar, antenna and trunk light. The driver's door window still doesn't go down. I'm getting some more fuses today! When I press the infrared key, the door will flash green and when I press it again, red. I can hear the vacuum pump for a few seconds afterwards but the doors aren't locking. I can also hear the window switch click when pressed as you suggested with the motor off. Hope the fuses will take care of the window problem. Incidentally, the fuses looked fine, but when I removed them, several just crumbled. Thanks again for your help. I love this forum!!
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Old 11-07-2006, 10:51 PM
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Join Date: Mar 2003
Location: Milwaukee Wisconsin
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Do the doors lock when you use the manual lock switch? The vacuum system actually locks the doors, the rear storage compartments, the glove box, the trunk, and the center console. A leak or bad actuator in any one of them can cause the whole system to malfunction. The vacuum is distributed from a manifold in the trunk on top of the vacuum motor. To diagnose the system, you will need a hand vacuum pump that you can attach to each vacuum line to find the leaker. Sometimes it's just an in-line check valve. But often it's an actual vacuum motor ( linear actuator ). In your original post you said the actuator in the driver's door was replaced. When I trouble shoot, I always start by looking at the last thing somebody else "fixed".
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  #7  
Old 11-11-2006, 07:20 PM
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Tecqboy,

my SL320 (97) experienced a near dead battery(still was able to start the car) and the top switch and rollbar switch became permanently illuminated. Also, windows needed to be synchronized, which I already did. Recharged the battery and still can not lower the soft top and the buttons stil stay lit. Is your read and reset code procedure doable by electical amateur like me?
tHANKS
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  #8  
Old 11-11-2006, 07:41 PM
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Join Date: Mar 2003
Location: Milwaukee Wisconsin
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That procedure will not work on models newer than 1994. After that, the control system was updated. Perhaps someone with a post 1994 Sl can chime in here.

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