It's the second one from the right and has a tire tread symbol on it. The car didn't have an owners manual to look it up with. Looking at pictures of other E-class on Ebay I noticed all the 500E's have it but I only saw one 400E with it.

That's the ASR switch. It's not an ASR defeat switch but I believe you are supposed to punch that button when you have snow chains on the car. Someone will have an owner's manual handy. It's my understanding that all 124 500s have ASR but it was optional on the 400s/E420s, which is the reason why I have the latter. I will not own a car with ASR - nothing but trouble, and usually inexplicable trouble.

The switch reduces the impact of the ASR system to 30% of normal (but as deanyel says, doesn't completely defeat it). As he says, it's intended to help get you unstuck if you have tire chains, but I've used it many times with dedicated winter tires without chains, too.

Personally, I wouldn't be without ASR (since I need to drive in snow this time of year). The 400E/500E produces enough torque that you get a lot of spin if you encounter slippery roads.

I'd also suggest you call 1-800-FOR MERC and order an owner's manual.

__________________
Steve
'93 400E

Actually that switch, often referred to as the snow chain switch, allows the wheels to slip up to 60 km/h (~35 mph) or so. In other words, it prevents ASR from kicking in until that speed. Once you hit approx 60 km/h or approx 35 mph, ASR is on once again.

To check if it works, engage the switch and drive, the light should go off around 35 mph...

__________________
Rainmaker
93 500E, 43k mi, Pics of upgrade parts
Evo II Wheels on Dunlop FM901 235/45x17s
94 Facelift
RennTech CF Airbox
RennTech ASR Defeat
RennTech Chip
1st Gear Start
97 Range Rover 4.6 HSE Vitesse, Yellow, "Tonka" (sold)

Just to clarify -- it does not actually completely defeat the ASR system under speeds of 35 mph. ASR will still engage at lower speeds with the switch ON (but the ASR system will allow more than usual wheel slip before it engages).

__________________
Steve
'93 400E

You can probably get an owner's manual from your dealer.

__________________
Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

I found a decent 500E locally for a price I like so I drove it. Hm.. FUN! BUT, one thing kept me from buying today. When starting off (in each case I was pulling out of a turn) there was a weird shudder that I thought might have been the trans but... it also almost seemed like an engine stumble too. But off idle rolling there was not shudder or hesitation and the trans seemed to shift better than the 300E.

I told them to service the car and I'd come back on drive it again. They are doing that over the next two days. Does this sound like something that ASR could be doing and if so, maybe punching that button might reduce/eliminate this and verify that it's the ASR?

Just wondering. Because for the price, I could probably have the tranny rebuilt and still be at market price. Body is not perfect and it was filthy... so.. once it's cleaned up it might show it self to be a rat too. *shrug*

__________________
-----------------------------------------------------