Mercedes Soft Top Controller Reset Procedure. R129 1990 thru 12/93.

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

To recover codes from 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 red (operate) top switch ( in the console ) will flash out a number of pulses.
Count the pulses and see the chart.

Short (close switch) 6 to 8 seconds to erase error code.

There may be multiple codes stored, so read / erase until all are cleared or the problem
Is located. Some codes may require reading / resetting twice before they will erase.

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.

2 = Limit switch, LEFT locked, soft top storage compartment cover.
3 = Limit switch, RIGHT locked, soft top storage compartment cover.
4 = Limit switch LEFT closed, soft top storage compartment.
5 = Limit switch RIGHT closed, soft top storage compartment cover.

6 = Limit switch LEFT locked, soft top fabric bow.
7 = Limit switch RIGHT locked, soft top fabric bow.
8 = Limit switch LEFT closed, soft top fabric bow.
9 = Limit switch RIGHT closed, soft top fabric bow.

10 = Limit switch LEFT front locked, soft top.
11 = Limit switch RIGHT front locked, soft top.

12 = Limit switch soft top storage compartment open.
13 = Limit switch soft top fabric bow raised.
14 = Limit switch soft top down in storage compartment.
15 = Limit switch soft top up ( secondary closing speed ).

16 = roll bar retracted switch.
17 = Left window failed to lower (limit switch open), bad fuse, or window relay on controller.
18 = Right window failed to lower (limit switch open), bad fuse, or window relay on controller

19 = Vehicle speed signal to controller missing or illogical.

20 = Hard top installed, no faults.

21 = Controller module / soft top switch circuit open.

22 = Roll bar switch activated.
23 = roll bar control unit not functioning.
24 = Roll bar crash deployed.

25 = contradicting switch inputs.

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

__________________
Resistance is Futile.