I think Larry might be right here. On my '94 wagon with that lousy ASR mode, if I hit the snow chain switch I get more RPM before the brakes engage. I usually can't make it up my drive way with snow if I don't turn the snow chain switch on. So I guess it isn't a complete shut down of ASR but a little delay? My wife's '99 E300 has a complete shut off but that is the 5 speed transmission and the wagon is the 4 speed.

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles