I've got a 190E '85 (2 litre motor), and it's a great car except for the Cruise Control. Other than being able to 'set' it, it mostly works. I get by this slight problem just by pushing the control lever up after reaching the wanted speed. But sometimes (especially when it's cold, like -1 to -3 degrees C ambient), the car will maintain its speed but has a misfire or something. Its that annoying that I have to turn it off and use the pedal instead. The car travels about a 40 kilometre trip each way to work and back at highway speeds, so having the CC is pretty convenient. Coming home in the late afternoon or night at whatever ambient temperature causes no problems.
Would anyone have experienced a similar problem, and if so, what did you do about it?

Thanks

 

When you say a misfirer, are you saying the engine backfires? or the cruise jumps on and off. On these early cruise controls, and according to which one you have, there were several systems. For example, my 79 450SLC has 5 options for cruise, not buyable, but whatever the factory installed you got. Usually when these cruise controls go bad it is either the amplifier below the dash, the stick on the column, is it loose, it should click into off, on accelerator etc and have no lateral movement except on reset and off. Also, there could be a vacuum leak. on the left side under the hood there should be a black with white stripe vacuum hose that leads to the acutator which is usually mounted toward the front of the car. Check to see if it is getting vacuum.

You can buy a hand vacuum pump cheap at most auto parts stores, but I see you are using C for temp, so you must out of the USA. Also the bowden wire could need adjustment. It is located on the accelerator mechanism clost to the fire wall, it has a black covering and there is a plasitc nut and it is attached under the accelerator at the point, usually on the right side in the engine bay, where the accelerator rod goes to the FI. The end of the bowden wire should rest without tension against its stop, the plastic screw is for adjusting the play.

Almost forgot the amplifier in some cars has a adjustment screw. on my car the screw is located next to where the plug for the stick on the column plugs in. This adjusts the accelerator rate of the cruise when you push the stick up.

 

Go to this site: http://diymbrepair.com/
Scroll doww to INTERIOR
Look for cruise control.
See if it helps.
Get back to me if you still have problems. I have another site on cruise control but not MB specific.
Shan

 

Thanks Shan for your quick reply.

The CC doesn't turn off under the conditions I've already described. The vehicle continues at the set speed, but the engine seems to continually and momentarily stall (just for a millisecond, or so) and then re-accelerates to its set speed: just like you may experience with a misfire.

The CC lever has four positions:
pushed down to SLOW DOWN (always works).
pulled towards the driver to SET (doesn't work most of the time).
pushed toward the roof to ACCELERATE (always works, oftentimes to the point of having to turn the CC off) and
pushed toward the dash for OFF (always works).

As you rightly guessed, I don't live in the US, but in near a small town (population 1200) in western Victoria, Australia and MB's are quite a rare sight at a motor mechanic hereabouts, although there are often mechanics that will have a go at anything. I tried one with my Range Rover and now avoid him like the plague.

I think that I'll have to make the five and a half hour road trip to Melbourne to get the CC seen to and/or repaired.

Thanks again.

 

Does that mean that site was not of much help?
Try this site. It tells you step by step how to trace the trouble in the cruise control.
As I said earlier, it is not MB specific but should be helpful.
http://www.the12volt.com/default.asp?
Scroll down to cruise control.
Shan

 

Shan I am going to check this site myself as the cruise on my 79 450SL won't hold speed. It accelerates but that is it. Adjusted the bowden wire, check the amp and it is OK and the actuator is OK and getting vacuum and electricity. I have a new stalk, just need to install it. Thanks for helping out one of our own.

 

Great site, perhaps it is my amp causing the problem??? I didn't look too deeply into the site, how is there pricing and service?

Thanks again.

 

Allan
I am from Malaysia. So I would not know much about the pricing.
Have you checked the speed sensor of the cruisse control at the speedo cable end?
In my son's car (MITSUBISHI) I had to dismantle it and clean the inside -the magnetic pole pieces and the metal strips -
to solve the same problem as you have.
Give it a try before you go for the amp.
If I remember well, there are supposed to be led indicators in the amp for checking the working of different sensors.
For manual transmission, if you push the forward just a few feet in neutral and ignition on, one of the led's should light up
if the speed sensor is functioning. If not, the sensor is suspect.
I have not tried on a MB. Both my 1962 w120 and 1979 w123 do not have cruise control. My 2002 w203 is fine so far.
Hope this helps. You should try to locate the speed sensor and give it a try.
Shan

 

Yes, I went thru the entire check and maintenance procedures outlined in the Mercedes Shop and Maintenance manuals for the cruise. I now feel it is the stalk itself. I have a new one, just need the time to install and a helper, as I can't bend too far over or neel due to my back problems.

I have another question for U. I bought a set of Euro lights for my W107 79 450SLC. They were supposed to have a schmetic enclosed. No wiriing diagram when I opened the boxes. When I installed them from out of the box, everything worked except the parking lights on the Euro, the directionals worked fine?? Also the OEM parking and directional lights, (attached under the bumper) did not worked at all.

I called the supplier and the first answer I got was, "no one around here knows how those lights are supposed to work." WRONG answer. I wrote a email to the supplier telling of my displeasure, and received a hand drawn wiring diagram. After spending 4 house cannibalizing my old OE lights for the proper wires and connectors, the Euro worked the same as I discribed above. Finally I really got mad and wrote a VERY STRONG letter voicing my displeasure with the company etc.

After receiving this email they sent me a printed wiring diagram, which had an extra connection After spending 2 hours disconnecting a gray wire from the OE's and wiring it to the Euro right side, I still have no parking light on the Euro and under the bumper no parking or directionals??? I emailed them back and they are baffled. I read part of the article about installing EURO's on the 126. But the Euro's for the 450SL have one single HD bulb and a single filament bulb for the directionals. Also, according to the Mercedes shop manual electrical wiring diagrams, any changes to the right side will automatically change or fix the left as the right is wired to the left side headlights and directionals, Fogs etc. But I now wonder is I am reading the diagram wrong. Strange thing is when I turn on the parking lights the Euro's are getting current to the sidemarker's both in the parking light setting and standing light settings. But only the directionals work. Any ideas????

The retailer really doesn't want to know nothing. As information the Euro's are geniune Bosch lights.