What has to be changed in order to reset the SRS Light?

Reseting the light isn't a matter of replacing any particular thing.

It depends on your car/SRS version as to how the problem (the purpose of the light is to indicate the system is shut-down due to a problem) is diagnosed. Early versions up through 1987 have no accessable self-diagnostics and must be circuit tested (preferably with the MB tool). From 88 through 93 self-diagnostics was through impulse codes readable with simple tools. From 94 on the systems are digital and can only be addressed with a scanner.

Fault codes suggest diagnostic strategy and the components are tested and when the problem is fixed the codes are reset and the light should go off after each self test (key cycle).

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The SRS light seems to be a recurring problem on the G class. At least it seems that way for me. My '90 model neede the light reset twice and my '95 now has the SRS light lit. The tech at my dealer said that just because the light is on the system is not necessarily shut down. It means that a fault code has been set but that the system will "try" to function normally. The recurring code on mine is too much resistance. There are brushes in the steering hub that allow the wheel to turn and keep electrical contact. At some point the brushes will need cleaning or replacement. I had this done on the '90, the contacts were still good, just needed some cleaning. This COULD be your problem. I found that the dealer was willing to pull the code for free while I waited. If you can find a dealer to do the same you have nothing to lose. Good Luck,Brent