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.
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.
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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