R129 1990 500SL Roll bar problem

[Langer]

Hi All,
We recently had our 500SL services by a local mechanic, who accidently made the mistake of starting the car with the looms for the roll bar and roof disconnected.

As a result of that, when reconnected, the rollbar automatically went into the upright position and now the roof will not function, nor the controls for the roll bar work.

I have tried holding down the roll bar batton for 10 seconds as suggested by other people to reset it, however that did not work. The indicator lights on the rollbar switch also do not light up.

We have checked over just about everything we can think of, removing the battery terminal to try and reset it, holding down the button, checking al fuses etc.

It is around a 1200km round trip to the nearest mercedes dealer, so I would rather fix the problem myself rather than drive 1200km for what could be a 2min quick fix.

Any suggestions?

Kind regards
Simon

[tecqboy]

You need to reset the controllers. You can do it yourself with a home made electrical switch "tool", or have the shop do it for you.

Mercedes Soft Top Controller Reset Procedure. R129 1990 thru 1995.

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

[Langer]

Ok, tried reading and resetting the codes, getting a code fo 1 for the roll bar which would indicate that everything was working perfectly there, however on the soft top, pin 10, I have been unable to read a code from it, even if I reset it, then request a code the light will just stay constantly on.

So, I am thinking it is something to do with the soft top controller, however the power windows work perfectly, and you can hear the relays click when you push the bottons.

Have checked all fuses, all fine, so not really sure what else it could be.

[Gilly]

Have you checked the fuses in the Base Module??
Gilly

[tecqboy]

Just a thought... You can't just look at the fuses, especially if you still have the original aluminum type. You must use a meter. They crack and corrode in unusual ways.

[Langer]

Ok, will go over the fuses again. I went over all fuses in the rear fuse box with a multimeter, but it might pay to do the rest.

....can someone please enlighten me as to what exactly a base module is