Added a "Cruise Control" indicator - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 10-17-2012, 12:03 PM

[This mod applies to all diesel and gasoline 124 models that DO NOT have an electronic accelerator system (400E/500E) and may also apply to models 123, 126, 201, etc. but the wiring may not be the same. Caveat emptor.]

I had always wondered why Mercedes didn't have any indicator to show that the Cruise Control was active. Maybe they figured it wasn't necessary but I always thought it was a nice touch and many other manufacturers have put such things in their cars. (I have since learned that the current Mercedes vehicles do have something to indicate speed control in the speedometer.)

Looking at my collection of diagrams, I realized that the wiring from the cruise control "amplifier" (under the dash, driver's side) to the "actuator" (somewhere under the hood) could also be used to turn on a light. Pins 5 and 8 of the amplifier control an electric clutch in the actuator; when the clutch is engaged the cruise control maintains a steady speed. If a lamp is connected between these pins, it will illuminate whenever the cruise control is active.

You can see in the picture that I used an LED as the indicator lamp. This LED is not designed to run directly from 12 Volts so I used a resistor in series, 240 Ohms, but anything close ("a few hundred") will do. The LED and the resistor are both common Radio Shack parts. Try #276-022 for a green LED and #271-011 for ta 220 Ohm resistor. [My picture shows a 240 Ohm resistor because that's what I had in my junk-box. The exact value doesn't matter -- a few hundred Ohms is fine.]

If you use an LED, remember that the positive (longer) lead must connect to pin 5 of the cruise control amplifier. The resistor goes in series with either lead of the LED. If you use an incandescent lamp, it doesn't matter, of course. Run the leads and put the lamp or LED somewhere out of the way but where you can see it while driving.

Rather that open up the amplifier's 14-pin connector plug (and risk an explosion of pins) I simply wrapped the wires around the pins of the amplifier. When the plug is put back on, the wires are trapped and can't move. This is simple, crude, unprofessional -- but it works! Use fine-gauge stranded wire, 24 - 28 gauge is plenty big enough. Make sure the wires don't short on the metal body of the amplifier. Secure with duck tape.

I went on to do something fancier as the following picture shows. It automatically dims at night and looks "factory" (actually it IS factory). This took a lot more work for the same result. If I get some positive responses I'll post the details. For most folks the KISS method is recommended.

Jeremy

JamesDean · #2 10-17-2012, 12:17 PM

Pretty cool! I often wondered the same!

For those of us who don't have the warning light area in the speedo like you do they could use one of the unused spaces in the idiot light cluster area..Provided your car has an extra space. Just put a weak incandescent bulb in there or something and have it light up like your circuit indicates. Maybe something off to the far right side, you know?

Jeremy5848 · #3 10-17-2012, 01:54 PM

Quote:

Originally Posted by JamesDean

Pretty cool! I often wondered the same!

For those of us who don't have the warning light area in the speedo like you do they could use one of the unused spaces in the idiot light cluster area..Provided your car has an extra space. Just put a weak incandescent bulb in there or something and have it light up like your circuit indicates. Maybe something off to the far right side, you know?

A good suggestion. maybe the place I have my "After Glow" light?

J.

JamesDean · #4 10-17-2012, 02:16 PM

Thats a good location. I'd pick something in a cool color that would not be offensive at night. I think getting the label thing to match up nicely would be tricky

Jeremy5848 · #5 10-17-2012, 02:34 PM

Quote:

Originally Posted by JamesDean

Thats a good location. I'd pick something in a cool color that would not be offensive at night. I think getting the label thing to match up nicely would be tricky

There are a lot of different label-makers so matching the existing Mercedes font can indeed be challenging. I used a Brother PT-1800 label-maker, its native "Helsinki" san serif font, and, in the case of my "After / Glow" label, 1/2-inch "white on clear" tape, which was the best match to the other warning lights.

I'd really like "clear on black" tape for other labels because the letters would glow out of a dark background, which would be neat and also wouldn't blind you at night, but Brother doesn't offer that tape -- yet.

The pictures below show how the "After / Glow" label was made. The "Cruise / Control" label was similar but I used "black on clear" 1/2-inch tape.

Jeremy

JamesDean · #6 10-17-2012, 02:38 PM

Quote:

Originally Posted by Jeremy5848

There are a lot of different label-makers so matching the existing Mercedes font can indeed be challenging. I used a Brother PT-1800 label-maker, its native "Helsinki" san serif font, and, in the case of my "After / Glow" label, 1/2-inch "white on clear" tape, which was the best match to the other warning lights.

I'd really like "clear on black" tape for other labels because the letters would glow out of a dark background, which would be neat and also wouldn't blind you at night, but Brother doesn't offer that tape -- yet.

The pictures below show how the "After / Glow" label was made. The "Cruise / Control" label was similar but I used "black on clear" 1/2-inch tape.

Sweet. I can get white on clear!

Epson LabelWorks™ Clear LC Tape Cartridge ~3/4" White on Clear - Product Information - Epson America, Inc.

3/4"..eh just trim it down with some scissors. I think some kind of muted yellow color might do..or green.

Jeremy5848 · #7 10-17-2012, 03:01 PM

Quote:

Originally Posted by JamesDean

Sweet. I can get white on clear!

Epson LabelWorks™ Clear LC Tape Cartridge ~3/4" White on Clear - Product Information - Epson America, Inc.

3/4"..eh just trim it down with some scissors. I think some kind of muted yellow color might do..or green.

Most places that sell plastic materials (gotta be something in Cleveland, eh?) will have plastic sheeting in various colors and shades. For the little bit that is needed you might even be able to get some free samples and cut to size. The existing label strip that Mercedes puts in the instrument cluster will be colored either "red" or "ick-yellow" depending on the warning light. You'll have to do some experimenting to see what you get. I used green over ick-yellow and it turned out green, thankfully. Careful not to get the strip too thick or it won't go back in the slot!

Jeremy

JamesDean · #8 10-17-2012, 03:05 PM

It just dawned on me that you could just use transparencies and a laser jet. Should work just as well. I probably wont get around to this until later but its good to have ideas down.

Jeremy5848 · #9 10-17-2012, 03:19 PM

Quote:

Originally Posted by JamesDean

It just dawned on me that you could just use transparencies and a laser jet. Should work just as well. I probably wont get around to this until later but its good to have ideas down.

That would give you a better range of fonts and font sizes but would you still be able to do white on clear?

JamesDean · #10 10-17-2012, 03:20 PM

Quote:

Originally Posted by Jeremy5848

That would give you a better range of fonts and font sizes but would you still be able to do white on clear?

I would imagine so. So long as you have a color laser. A black and white printer won't print white lol.

dcotejr · #11 10-17-2012, 06:24 PM

I suspect not unless I misunderstand what you are trying to do...

Wavelengths of colored light adds to white; pigments/dyes subtract out wavelengths from white light and go toward black in the right combinations.

The only way to get white characters on clear would be with a white pigment, like titanium dioxide.

( I am a technical manager in the printing industry and I deal with such things regularly...)

BUT -I love the ideas! Keep 'em coming!!!
Don

JamesDean · #12 10-17-2012, 06:26 PM

Quote:

Originally Posted by dcotejr

I suspect not unless I misunderstand what you are trying to do...

Wavelengths of colored light adds to white; pigments/dyes subtract out wavelengths from white light and go toward black in the right combinations.

The only way to get white characters on clear would be with a white pigment, like titanium dioxide.

( I am a technical manager in the printing industry and I deal with such things regularly...)

Hmmm guess the label maker is the way to go then! I bow to your knowledge!

dcotejr · #13 10-17-2012, 06:35 PM

No need to bow.

I have learned so much on this forum, and am just trying to give back a little...

JamesDean · #14 10-17-2012, 06:45 PM

You know, I thought about it for a second at work today. How in the hell would you make white since normally all paper is white and to show white..you'd simply not put ink there..

Jeremy5848 · #15 10-17-2012, 08:00 PM

Could an inkjet printer do white on clear? I don't think mine would -- maybe yellow on clear at best. I don't even know how the label-maker does it but it does.