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cruise control / tempomat problem

15K views 19 replies 9 participants last post by  feras 
#1 · (Edited)
hi guys... has anyone got an idea about the cruise control ? where is the control unit ? mine is 1990 sl500 and the cruise control not working at any speed. i tryed to find information about the system in all data but nothing about the cruise control. please if anyone got an idea about this system reply to me.
 
#2 ·
Hi Feras, I don't have the answer but it's called 'cruise control'. Try submitting those words into the search facility.
Best of luck with finding the fault :thumbsup:
 
#4 ·
The problem is most likely the Cruise Control Module. It is supposed to be a common thing that breaks on the older model 129's Most of the dealers say leave it that way unless you do alot of highway driving. I hate broken stuff so I had the dealer fix it. Wasnt a cheap fix if I recall around a grand. Anyway if your handy check some of the sites that sell the module as I am almost sure that is what it is. Good Luck.
 
#5 ·
RedLiner said:
but it's called 'cruise control'. Try submitting those words into the search facility.
..or "tempomat", check the German eBay for used modules and you will find one sooner or later (a lot cheaper than at the dealer's)

Good luck!

BTW, do you remember anything that could have caused the failure? Such as disconnecting and connecting the battery? Or jumpstarting the car? Or recharging the battery..?
 
#7 ·
On my 1990 500SL there is no cruisecontrol / tempomat. Someone has told me that if you have ASR on the car, all you have to do is install the handle, because all the elecronics lies in the ASR unit or something. I know that this is a fact on other cars.

Anyone knows anything about this?
 
#8 ·
feras said:
hi guys... has anyone got an idea about the cruise control ? where is the control unit ? mine is 1990 sl500 and the cruise control not working at any speed. i tryed to find information about the system in all data but nothing about the cruise control. please if anyone got an idea about this system reply to me.

Hey....

I have the same - 1990 500SL.

Not sure why you can't find the info on ALLDATADIY. I just looked it up and there is soem info available (link for cruise control on the first page after you log onto to the car's info).

It's got some info - but doesn't really tell you much about where to locate the control unit (if it has one). There is something about ASR and Cruise Control Amplifier (Cruise Control Inoperative After Amplifier Replacement).

I did however find this info: "The coding plug is connected to the control unit. On 190D and E models, the control unit is attached to a plate located in the right hand front foot well. On all other models, the control unit is located under the left hand side of the instrument panel. While compressing coding plug locking lugs, disconnect coding plug from control unit."

There are some diagrams (under cruise control module) for the location of:
Locations
. CC/ISC Control Module
. EA/CC/ISC Control Module

I am guessing CC = Cruise Control. The location for these are under the hood - passenger side top corner (US model) closest to the side mirror. It shows 5 small rectangular units. The digram has arrows pointing to the units with labels such as "N4/1", "N3/2" .. etc. To be honest I have no idea what they are.

Some more info i just found on ALLDATA for 500SL (90):

Control Unit Service and Repair
Disable airbag system, refer to MAINTENANCE PROCEDURES/AIRBAG ARMING & DISARMING.
Remove left hand side instrument panel undercover, if equipped.
Disconnect electrical connector from control unit.
Remove control unit to pedal bracket attaching screws, then remove control unit.
Reverse procedure to install.

ASR unit is located same area I mentioned before. Not sure if they are labelled on the car itself... but on the diagram they are:

Component Name ASD control module (in Module Box) - Component ID N30/2

..................................................................

It all looks a bit too complicated to me. So, if you are not autoelectric-mechanically inclined, you may need to see someone else to have it fixed properly.

I also read somewhere on here that the cruise control system is very sensitive to the type of break lights on the car. If they are different to OEM, then the cruise stops functioning. I think it has something to do with the cruise being linked to the break lights and the breaking system. Not entirely sure... but worth finding out.

Hope that helps!

Over out...
Sapps
:)
 
#9 ·
sappster said:
I also read somewhere on here that the cruise control system is very sensitive to the type of break lights on the car. If they are different to OEM, then the cruise stops functioning. I think it has something to do with the cruise being linked to the break lights and the breaking system. Not entirely sure... but worth finding out.
I don't know the system but when i saw this about the brake lights I couldn't help thinking that maybe when you are on the cruise and touch the brakes the cruise will automatically and immediatelly disengage - so maybe there is some truth to the sensitivity and OEM bulbs? Just a thought, no knowledge here either... :)
 
#10 · (Edited)
feras said:
hi guys... has anyone got an idea about the cruise control ? where is the control unit ? mine is 1990 sl500 and the cruise control not working at any speed. i tryed to find information about the system in all data but nothing about the cruise control. please if anyone got an idea about this system reply to me.
This link will show the location of the "Cruise Control Actuator", (4D), and "Cruise Control Amplifier", (3D), this is for the 190 model, try to find the diagram for your model. Mercedes used the same system for all models, but the location of the units are different, if you find the "Actuator", the motor that moves the throttle linkage, you should beable to trace back to the other units:

http://www.performanceproducts4benz.com/Drawings.aspx?bmid=14
 
#13 · (Edited)
The correct spot... Hmmm, there has been a few books written about the subject... :-D (pardon me...)

But in this case, if its anything like this -95 W140 S500 coupe (M119) then look for the "F23 box" and the "N4/1 = Electronic Accelerator/Cruise Control/Idle Speed Control Module" as per this link:

http://pages.prodigy.net/jforgione/MB_X11.html

BTW the 1990 has a 16 pin connector not the 38 pin one, not sure about the "F23 box" but have a look... Then if still no joy call Bob Terry! :)
 
#15 ·
SLNorway said:
On my 1990 500SL there is no cruisecontrol / tempomat. Someone has told me that if you have ASR on the car, all you have to do is install the handle, because all the elecronics lies in the ASR unit or something. I know that this is a fact on other cars.

Anyone knows anything about this?
This is right. With cars that have ASR, the cruise control function is integrated into the throttle positioning control module, N4/1.

Non-ASR cars have a dedicated module mounted to the inner fender in the compartment that houses the fuel injection, ABS, and other modules. It's a black box.

Feras, I would remove the connector to your cruise control module (or N4/1, if applicable) and check the relevant inputs. These would include the cruise control switch and the brake switch. If you have no ASR and the dedicated module, see this link for more information on testing: Test Procedures - Table of Contents. GDL is a company that rebuilds the control modules.
 
#16 ·
bobterry99 said:
This is right. With cars that have ASR, the cruise control function is integrated into the throttle positioning control module, N4/1.

Non-ASR cars have a dedicated module mounted to the inner fender in the compartment that houses the fuel injection, ABS, and other modules. It's a black box.

Feras, I would remove the connector to your cruise control module (or N4/1, if applicable) and check the relevant inputs. These would include the cruise control switch and the brake switch. If you have no ASR and the dedicated module, see this link for more information on testing: Test Procedures - Table of Contents. GDL is a company that rebuilds the control modules.
Thanks bobterry, do you know how to install the handle? Someone said it should be a connector on the left side of the steering wheel somewhere around the light switch, under the dash.....?
 
#17 ·
SLNorway said:
Thanks bobterry, do you know how to install the handle? Someone said it should be a connector on the left side of the steering wheel somewhere around the light switch, under the dash.....?
Heja Norway, sorry to bump in as I'm not Bob, but have a look at this video (you don't need to do ALL they've done, just the things to get your hands in to the area where the tempomat would be):

http://www.classic-roadster.de/albums/Filme-r129-demontage-cluster/R129D3.mpg

Also, you'd need to remove the steering wheel first - here's a link to a certain Swedish site :-D ... It's in Swedish but I suppose its no problem... And it has pics too... :-D

<<<Mercedes Scandinavia>>>

The handle I suppose you could find at the German eBay...
 
#18 ·
thanks guys for reply... my car has the asr and i think i ganna check the throttle positioning control module...maybe the connection>> but i got the stop lamp amber indicator on and got one of the stop lamps not working so does it stop the cruise control from working??
 
#19 · (Edited)
feras said:
but i got the stop lamp amber indicator on and got one of the stop lamps not working so does it stop the cruise control from working??
Possibly, not sure and don't know... But I would definitely replace the brake light bulbs with originals (if the remaining functioning one is not original I would replace that as well just in case the sensitivity mentioned previously is true) and then see if the warning light is gone and if the cruise then works. Very cheap and easy as opposed to a visit to a dealer... Or a new/used control module... And PLEASE PLEASE PLEASE let us know the developments...? :)

PS not sure if you possibly have fault codes or not, but I would start with the above and see what the results are.
 
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