Same problem with our 94 C280, took it to Chuck in Houston. Found out the passenger seat belt switch was the fault. So the SRS would not deploy if need be. Will get it replaced under the extended warranty. MB dealer in Houston wants 100 per dashlight for diagnostics. Hard for me to understand since the electronics is already hooked up to run the tests. Local tech did it for 65.00 and in less than 1/2 hour and is a great guy to boot. You Houston guys give him a call!
Find you a tech you can develop a trust and relationship with worth the effort. LH