DIY ASR Defeat Switch
 

vcci wrote
I thought it would be great to start a unique thread on this topic so that any/all who are interested could easily find the info.

vcci, the floor is yours

Dear vcci & aldedmon:

By all means please post or email to me instructions on how to build an ASR defeat switch.

I want to rid my car of ASR and have a limited-slip differential installed. So far, Renntech estimated that this mod. would cost me $3K at their shop, but if I defeat the ASR first, their price should come down to $2K.

Thanks for all your help.

The limited slip diff is expensive if you have ASR because there are components inside the diff that support the ASR. If you "defeat" the ASR it will still be expensive to install the limited slip because ASR is still there, it's just not operating. You could fit a non ASR diff I suppose.

Matt.

Ok this is the deal. I am not too familiar with the electronics of cars but I will do my best to tell you everything I know.
After searching this site for about 2 weeks trying to figure out why it costs almost $1000 to get this damn ASR off in my car I ran into a post that showed a diagram of the ASR defeat system and the way it works. I also found complete instructions for installing the ASR defeat made by RENNtech and had a friend of mine take a look at it. After just a minute of looking at it my friend says "this is a piece of cake, how much did you say this costs?" 20 minutes later he tells me to take it for a spin and see if the wheels are spinning, and guess what, those tires were burning like no other benz ever burned. What you need to do first is find the installation instruction posted somewhere on this site, I cant find them again for some reason. Now, find the box located near the firewall on the driver's side being help by 4 allen screws, remove the the complete box, find the computer named ASR and remember what slot in went in to. If you look at the instructions it will give you colors of the wires and numbers, all my friend did was disconnect those 3 wires. This will completely turn off the ASR the car will burn rubber like you wont believe. Please excuse my limited knowledge of the process. My friend now made for my car a box with 3 modules or relays ( i dont remember which ones he said but I will ask him and post again) located inside, he will connect a switch to the box with modules or relays and I will be able to tur the ASR system on and off. I was gonna buy an original W140 ASR switch and put it on the panel next to the snow chain switch but I figured having it mounted under the steering column would give me an advantage of having it off when I give to my wife to drive and not having her mess around with too much power for her to handle. I have been driving the car for about 5 days now and can tell you that this has completely changed my views of te 500E, it is simply a 4 door porsche, amazing performance, a sedan like no other etc. I have read posts regarding the ASR defeat is kinda like keeping the snow tire chain system engaged for higher speeds, NOT TRUE, the wheels are still being kept from spinning. The ASR light has been on since this was done but I'm sure it will turn off after my on/off switch is switched to off. Let me know if you have any further question and I will try to answer them the best I can or I will ask my friend and get the right answers for you. ANYWAY SORRY FOR THE LONG POST BUT IT SURE BEATS PAYING ALMOST $1000 FOR SOMETHING SO SIMPLE.

vcci,

Does diconnecting these wires affect the ABS System?

NOT AT ALL

vcci:

The ABS and ASR work off the same speed sensors, so my understanding is that if one's offline, then so is the other. Have you actually invoked ABS with a panic stop or two? Please let us know

Also, I was not able to locate any box on the driver's side as you mentioned - can you post a picture or more detailed instructions on how to find it? Thanks in advance:)

I have not envoked the ABS system but I will later today and post results, although I am pretty sure the ABS is functioning properly. The box I was refering to is on the passengers side next to the firewall.

Here is one of the threads referenced in vcci's post
 

RennTech Diagram
http://www.peachparts.com/shopforum/showthread.php?threadid=26660&highlight=ASR+defeat

Thank you Aldedmon for posting the instructions. As you all can see this will walk you through the steps of how to defeat your ASR.
NOTE: While looking for the wires at the connection of the ASR computer control unit we noticed that the colors were not as stated in the instructions, my friend went by the wire numbers and they were correct.
So far I have not had the switch installed in the car but if you just want ASR off this will do it. I will keep you informed after the switch has been installed.

That's the CAN Bus. I'll check it out (and the 4 allen screws simply hold the cover on-must pull the appropriate module out)

has anyone tried it? i'm just wondering if anyone tried it what they thought and how they liked it. I personaly love it.

DIY ASR Defeat
 

I do have a very good understanding of electronics, as I deal with them on a daily basis, I can read electrical/electronic drawing easily and I think that something like this will work perfectly. I've recently been doing my own research on how to defeat the ASR on my '97 C36 AMG, while I haven't read completely through this thread my first impression is that it is probably very true. I've found some technical data that states that the ASR is completely disabled when the stoplamp switch(S9/1) is engaged, this is the switch that is actuated by the brake pedal - turns brake lights on and off. It is a 4 pole switch with 2 of the poles going to the ASR control module (N47-1). So as the brake pedal is pushed it defeats all function of the ASR, but natrually it lets the ABS function fully. My theory is that with some simple rewiring of the ASR switch, one could "trick" the ASR control module into believeing that the brake pedal is constantly applied, and TaDa... no ASR, and no trouble with ABS. Making it switchable means one can have all the benefits of ASR, but also turn it off for more fun. I have not had the time to try this out yet, and as it is the dead of winter here where I'm at ASR is greatly appreciated. I'm planning on trying it out this spring. I don't know if this is the same conclusion/method that vcci is using but I know it can be done. Post back if someone wants more details on my theory... good luck.

More DIY info
 

After looking at the info in the thread more closely I'd be very careful while making modification like this, while I'm sure it works as advertised I'd be cautious. According to the information and drawings I have the wire/terminal #'s of 25, 35, and 37 per the RennTech instructions are for the ASR/ESP/ETS hydrualic unit. I'd be VERY careful messing about with this unit and it's wiring/control. I do know that there are (2) different versions of the the ASR control module (N47-1) and I know the drawing I'm looking at is for my 1997 C36 (W202). So maybe those wire/terminal #'s do apply to the 500E series of cars, but I'd be careful of trying on a different model without some research. I'm not trying to burst anyone's bubble, just a word of warning... Good luck.

Tifosi
I don't know if this would work for the C36 or not but if it can be don on the 500E than I would think if one found the diagram for the C36 it would work just as good as it did for my 500E.