DIY ASR Defeat Switch - Page 5 - PeachParts Mercedes-Benz Forum

TIFOSI · #61 06-14-2003, 01:03 AM

Michael - your right the handling is pretty much flat, it's very new to me still, so I'm still learning the "in's and out's" of it. You are much more involved in "driving" the Ferrari then you are in the C36... It is much to easy to go very fast in the Benz!! Not that this is a bad thing!! The Ferrari is 23 years old, and you feel it - no power steering, no ABS, very much driving the car, and I really wouldn't have it any other way!!

Anyway, back to the ASR switch, don't know if you have access to skematics of your 500E, but if you do could you find a desciption of the 3 wires you are wiring through you relay? If not you might want to check out the alldata.com site I referred to earlier, I was very impressed with the overwhelming amount of information they have. You pay $20-$25 per car and get acces to basically an online tech manual, procedures, drawing, diagrams, hints/tips, factory updates, etc, really a good resource. Good luck with your wiring and let us know how it turns out!!!

Michael · #62 06-23-2003, 08:59 AM

Now it's time to figure out how to wire this sucker. Being an electronics neophyte (know-nothing newbie), I'd like a little help.

Here is what I've done so far:
* Secured the MBZ "ASR Off" switch-it's been deemed unsuitable, since it's a "moment" switch that only closes its circuit momentarily - I need a true on-off switch to power the relay. So, I picked up a 500E rear dome light switch, which does just what I need, took them both apart and changed the covers. Now, the dome switch says "ASR Off". When I activate/push the switch to the up or On position, the circuit closes until I flip the switch off. Now, having identified both the ground and the power pins, I need to understand the third....I believe it's to illuminate the LED, and I'm inclined to hook it up to the interior lights. See attached picture of the interior of the switch.

* Secured a 4-pole relay

Now, to wire it all. As I see it, I should run an ignition-on power lead to the (+) side of the switch. The ground lead would then run from the (-) side of the switch to the (+) lead on the relay. The (-) lead of the relay would then go to a chassis ground. But what about the power going to third pin on the switch, the one that lights the illumination LED? From the factory, the illumination switch ground likely goes directly to chassis ground, so the power going to the illumination lead simply went on through to ground. But now, that ground (if I'm guessing correctly) goes on to the relay. Thoughts??

I believe I have the rest figured out, but I need help from you electronics geniuses out there. HELP!!

shanta · #63 06-23-2003, 11:38 AM

I am no electronics person by far, but can't you splice into the illumination wire from the next switch over? Say the snow chain switch?

Alternatively you could ask Carl @ Bergwerks. He may be able to help you with this wiring. Carl@BergWerks.com

Michael · #64 06-23-2003, 12:01 PM

Actually, since it's going to replace my now unused Fader switch down by the window switches, I'd grab the illumination lead intended for the fader switch and use that. No problem. However, what I don't understand is how that lamp would be grounded, since the ground pin on the new switch is now going to carry power along to the relay, THEN to ground. Since they'd be wired in series, would that work?

shanta · #65 06-23-2003, 12:47 PM

Did you check out the way Renntech did it? Here is the link again ASR defeat

Michael · #66 06-23-2003, 12:54 PM

Thanks, Shanta, I have indeed referenced that thread. However, it doesn't help me in this case because it appears the way we're achieving our solutions might be different (I'm not actually sure) as to the wiring. It appears the RENNtech solution uses the functionality of the ASR moment switch, whereas I'm simply wiring in a relay that'll open those 3 wires going to the ASR module. Probably doing the same thing, bottom line. But I still need help wiring it, so please keep the ideas coming!

shanta · #67 06-23-2003, 01:00 PM

How does the "real" rear light switch get power, ground & illumination? Can you tap into that? Since the switch you are using is that of a rear light switch can it not be wired in the same manner, just running to the relay?

I am not an electronics person at all, so I am just literally throwing ideas out there.

I hope you get this figured out soon, because I want to do this on my car

Michael · #68 06-23-2003, 01:51 PM

Since the switch is being utilized differently, the current switch can't be used as a reference since all it does is illuminate a light bulb; so, I can see how the LED would simply be illuminated and would use the same ground at the switch that the dome light circuit uses. In my case, however, the ground at the switch is going on to power the relay. However, I'm wondering if I should run (ignition switch "on") power to the relay first, then have the ground circuit be closed/opened by the switch. That would retain the switch's ground as a ground, no?

TIFOSI · #69 06-24-2003, 03:33 PM

The ground terminal on the switch should only be for the light in the switch. The switch is simply that, a switch... it has a set of contacts used to make or break a circut. The circut you'll need to be making and breaking will need to be a 12vdc (+) circut to supply voltage to the coil of the relay.
I'll try to explain how I think you'll need to run the wiring... I think!! If you have a ignition switched 12vdc(+) run it to the switch, this (+) will be used to power the relay, and most likely the LED in the switch, so be aware of which terminal it is on the switch. If you have a multimeter, find which pins on the switch are the contacts, you'll have continuity in one switch position, and not in the other, these are the pins you'll need to run the 12vdc(+) through. One pin will likely power the LED as well, so keep that in mind. Now you'll also need a ground at the switch, but this is for the LED only, you can pick up a ground for the relay elsewhere, don't worry about routing a ground through the switch for the relay. Once you have the switch in place, run the switched (+) from the switch to the (+) terminal of the relay coil. The (-) of the relay coil can just run to a suitable chassis ground. This way the switch is supplying the (+) voltage to the coil and hence operating the relay only when the switch is in it's maintained, made state.
Next you can run the 3 ASR circuts through the NC (normally closed) relay contacts. This way when the switch is off no voltage reaches the relay coil, the ASR circuts are made (NC) and ASR works as normal, when you switch the switch "on" voltage passes through the switch, to the coil of the relay, the relay operates, the relay contacts change states (open up) the ASR circuts break and your tires spin wildly and produse insane amounts of smoke!!!

Your switch is the only part that I might be way off about, I'm not sure of the exact type of switch you have or all of the details as far as the LED. But the basic design of the relay circuts should do what you want. ... Good luck!!!

TIFOSI · #70 06-24-2003, 03:50 PM

Hope this helps

Michael · #71 06-24-2003, 04:52 PM

I couldn't read that attachment; could you email it to me @ mcurcio@sbcglobal.net? Thanks.

As to the circuit, there are only 3 pins on the switch, and it appears based upon my testing that both the LED illumination and the "light" circuit use the same ground. So, I'm inclined to proceed as I last posted and run power to the relay first, then open/close the ground side with the switch. Whaddaya think?

TIFOSI · #72 06-24-2003, 06:53 PM

I wouldn't use the ground circut to switch the relay, not really good practice... Although it would work. The three pins would be for 12vdc (+), to power the LED and to run through the switch contacts to power whatever you wanted to power up, (ASR relay?) the ground pin is to ground the LED, and also for the old set up when the switch was used to control the dome light it provided a ground point for the dome light. Although the switch may be designed to break the ground to control the dome light, but I kinda doubt it???
I'm guessing here but from the picture you sent it looks like the switch has three pins, 1st pin is for 12 vdc(+) this is tied to both the "common" contact of the switch, and to a resistor, (voltage "knock down" for the LED) to the LED for the switch illumination. 2nd pin switch contact, will pass the 12vdc (+) on to what the switch is tied to. 3rd pin, ground for LED and in the original case the ground to the dome light. I'd guess that is how it's set up, but if I had a nickel for every time I've guessed wrong I could afford a new E55 AMG!!

Good luck, let us know how it turns out.

Michael · #73 06-25-2003, 11:26 AM

Okay, I decided to build this circuit on the bench before proceeding with the install. I ran power to the LED pin, then grounded the (-) pin; with the switch off, no light-but with the switch on, the LED illuminated.

I next sent power to the relay circuit pin on the switch, then ran a wire from the ground (-) pin on to the switch to the (+) pin on the relay, then from the (-) on the relay back to ground. When the switch was activated, the relay actuated. Good!

Next, I connected power to both the LED and the relay circuit pins on the switch, and connected the (-) pin on the switch to the (+) pin on the relay, then from the (-) on the relay back to ground. When I energized the circuit & turned the switch on, it blew a fuse on the power source. I re-checked my wiring, powered it up again and Poof went the fuse. Any thoughts out there, or do I simply forget about illuminating the LED circuit? This is WAY over my head....

TIFOSI · #74 06-25-2003, 08:06 PM

What exactly are the labels on the switch pins, pluses, minuses, what???

I believe that you should have a (+), (-), and a 3rd??? what is the 3rd labeled? From looking at the photo you attached the, (+) is to pass through the switch contacts, and power the LED when actuated, the 12vdc (+) will also proceed "out" the 3rd pin. The (-) is only to supply an negitive ground return for the LED circut, it shouldn't have anything to do with the relay you are trying to drive with the switch. Again without actually seeing your switch I might very well be wrong and apoligize if I'm only adding to your confusion. I don't know what you are using as a power supply (battery, bench top power supply, etc) but try this for me:

1. Run a 12vdc (+), from your supply battery, directly to the pin (+) you used to make the LED come on when you switch your switch.

2. Run a 12vdc (-), from your supply battery, to the switch pin marked (-).

3. Switch the switch on, the LED should come on, and you should have 12vdc (+) coming through the 3rd pin, check for this with a test light or multimeter. Switch the switch off and te LED will go out, and you will no longer have 12vdc (+) at the 3rd pin.

4. If this is the case then run a wire fron the 3rd pin to the (+) of the relay, and a wire from the (-) of the relay all the way back to the (-) on the supply battery. Again try the switch, the LED should come on and the relay should actuate. If it does... then there you have it!! If not, then I'm not understanding how your switch is working and have led you down the wrong path - Sorry. Again Good Luck!!

Michael · #75 06-27-2003, 10:07 AM

The pins are labeled 1,2, and 3, top to bottom.

Okay, using a 13.0 volt source (portable air compressor with its own rechargable battery & aux. 12V cigarette-lighter style output) I ran power to Pin 1, which is the one that lights the LED. I then checked Pin 2 (believed to be the LED ground) and could measure 11.58 volts flowing out. I then checked Pin 3 (the "other" pin) and it also had 11.58 volts coming forth.

Test #1: Ran power to Pin 1. Grounded Pin 2 (back to power source) and with the switch on, the LED illuminated. Switch off, LED off.

Test 2: With power to pin 1, I grounded Pin 3. LED illuminated reagardless of switch position.

Test 3: Power to Pin 1. Wired Pin 3 to (+) side of relay, relay (-) back to (-) at power source. The relay has a small LED itself, which lit up, but the relay did not actuate.

Test 4: Power to pin 1. Wired Pin 2 to relay (+), relay (-) back to (-) power source. Relay LED flickered, but relay did not actuate.

Test 5: Power to pin 3. Measured voltage at pin 2: 13.0 volts. Wired the relay into the circuit and it actuated! At least this switch will work one way or another. Switch LED did not light (Pin 1 was not used during this test)

Further thoughts?