Removable Soft-top Module (RST)

Opening and closing problems associated with the convertible roof can mostly be traced to mechanical malfunctions such as faulty micro switches, hydraulic pumps, and electric motors. For example, if your early SL has an instrument cluster failure, the RST will not operate, as the VSS signal comes from the instruments. However, the ECU can also succumb to electrical malfunctions, and then must be replaced or repaired. Our test bench equipment can quickly diagnose ECU problems and help trace your main source of problems. Multiples versions of the RST module exist for the R129 :

When diagnosing a convertible top issue, a schematic of the opening and closing sequence is helpful. The micro switches involved in the process are critical to correct operation. The following diagrams show switch timing, and DTC errors.

Operation of the RST module
Diagnosing a faulty micro-switch

One of the main sources of failure in the Gen I RST, are corroded or worn out relays. There are a dozen miniature relays inside these modules, and unfortunately, are obsoleted and neither stocked nor manufactured anywhere in the world. Originally produced by Becker, part# 649 627, they have a non-standard miniature footprint, incompatible with any relay on the market today. MBCluster has manufactured one-of-a-kind PCB adapter boards to mount OMRON G8N-1 sub-miniature relays in their place, as a solution for replacement.

Another very highly recommended preventative, and simple upgrade, is a copper/brass fuse upgrade kit. Available on EBay and many other online places, this kit replaces the old aluminum fuses prone to bi-metallic corrosion. This upgrade is well known to fix many issues due to rust and corrosion on contacts causing electrical problems in the SL.

MBCluster can restore your RST module to original specifications, and provide proper operation of your convertible soft-top. Contact us to discuss your module, issues you are having with it, and what diagnostic steps you have performed thus far.

Sending In Your Unit

  1. Fill out the online Repair Form, and include it with your unit :

  2. International customers, ex. United states, Europe, must fill out the customs documented, and follow the shipping instructions available here.

  3. Bundle the unit up in ample padding and place it in a sturdy box. Address is located at the bottom of the Repair Form. Please note : Only USPS may be used for American shipping! Canadian shipments may use private couriers such as UPS, FedEx, etc., all other countries must use their federal postal services.

  4. Once we have received the unit and diagnosed the fault, we will e-mail an update. If you are satisfied with the diagnosis, we will begin repair accordingly. Final payment is done using the easy PayPal system, with Invoice sent in the email exchange. If for whatever reason, you have decided to decline service, or service is not possible for your unit, a shipping charge is required to send it back.


RST Repair $500

Pricing is in Canadian Dollars (CAD). Note: All Canadian residents must add their province's applicable taxes (HST or GST). United States and other foreign countries do not add taxes.
Return shipping fees are not included, and depend on method and carrier desired. Services with tracking numbers are mandatory.

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Contact Information:

James Kouramanis
8 Blacktoft Drive
Scarborough, Ontario
Canada M1B2M6

Hours of Operation:

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