Mercedes-Benz Forum banner

1 - 20 of 36 Posts

·
Registered
Joined
·
136 Posts
Discussion Starter #1
Hi All

Great forum. It's provided me with a lot of help in choosing and fixing my 230E. So for my first post I'm contributing this basic info which I battled with at first. I hope it's helpful to others.

For anyone who's cruise control isn't working and wondering how to get to the cruise control amp under the dash this is how I did it on my '92 W124 230E manual (Being South African this is a Right hand drive vehicle)

To remove the kickboard under the steering column

1. Put your finger into the side of the ignition key hole, you'll feel that the material is made of rubber, pull firmly to the right (the plastic lugs behind the plastic trim aim to the left) *Maybe it's the other way round on a Left hand drive vehicle* and the ignition cover should come off (note the three black holes in the pic below, that's where the lugs snap in) Remove the screw and bolt that you can see in the pic.



2. Now pull the Headlight control knob out, this was a bit difficult but you can do it with your thumb and index finger, I got it out by turning the headlight knob all the way to the left and then pulling it out.

Once you've got it off

3. Remove the nut shown in the pic below. Best to take out the little lightbulb first so you don't break it.



4. The black plasic trim clicks out if you pull to the right.

5. Now you'll see 3 brass bolts that need to be removed. Bear in mind that the two screws you can see under the parking brake release DO NOT need to be removed, NOR does that tricky looking screw that you can see when you pull out the parking brake release.



6. Now down at the bottom under the dash, (easy to find, no pic necessary) remove the two bolts on either side and the screw in the middle

7. Now gently pull the dash out and you'll see the cruise amp box (the silver aluminium box in the pic) you do not need to unscrew the two phillips screws, just unbolt the bracket, the two nuts holding the bracket are visible in this pic. For reference the round thing on the right hand side of the pic is the headlamp knob



8. Now you've ubolted it pull the cruise amp towards you and gently release the 14 pin connector from the back.

9. The circuit board is encased inside the silver aluminium box, you'll need to gently prize the kinks open to get the board out.

10. Go ahead and do the resoldering or cleaning of the board and good luck. I don't have the skills to resolder so I gave the board a cleaning with surgical spirits and a tooth brush but to no avail.

11. When you reassemble it's best to reverse the order, so start by bolting in from the bottom.

Good Luck
 

·
Registered
Joined
·
186 Posts
Thanks for the tip! I'm sure a lot of folks will benefit from that. Also just so you know, I've seen references in forums here to places that will rebuild the amp for you for a fee, don't recall the names but a search should yield the results you need. Now that you can take it out, might as well benefit from your hard work!
 

·
Registered
Joined
·
99 Posts
St3ve, thanks for your contribution!

Please let me know the function of cruise control and what happen when the cruise control amp malfunction to the '92 W124 230E?

4484
 

·
Registered
Joined
·
136 Posts
Discussion Starter #4
4484 said:
St3ve, thanks for your contribution!

Please let me know the function of cruise control and what happen when the cruise control amp malfunction to the '92 W124 230E?

4484
Hey 4484, speed control or auto cruise see here: http://en.wikipedia.org/wiki/Cruise_control

And when it's not working you just don't have that feature. The car still runs fine.
 

·
Registered
Joined
·
262 Posts
St3ve

THANK YOU

Followed your instructions. They sure helped me to get the amplifier out (with a little effort mind you). 1988 300E.

jb
 

·
Registered
Joined
·
1,547 Posts
Got it out and cleaned it with electronics cleaner, no change.
I think the box is out.

It's funny one day it started working, for only about 10 minutes, and that was that. Hasn't worked ever since. I think it was just saying goodbye before it died. :D
 

·
Registered
Joined
·
42 Posts
Oops... while disconnecting the 14 pin connector from the aluminum box, the connector fell apart and all the 14 wires are now hanging in the air. I have no idea how to arrange them back in the connector! Any ideas?

The hanging wires:


The back side of the connector, with numbers from 1 to 14 on it, but no reference to which color wire goes to what number...
 

·
Registered
Joined
·
1,547 Posts
Oops... while disconnecting the 14 pin connector from the aluminum box, the connector fell apart and all the 14 wires are now hanging in the air. I have no idea how to arrange them back in the connector! Any ideas?

The hanging wires:


The back side of the connector, with numbers from 1 to 14 on it, but no reference to which color wire goes to what number...
Have you tried a local shop or dealer and see if you can pick up or they can fax/email a copy of the wiring diagram/schematic???
 

·
Registered
Joined
·
1,547 Posts
Not yet... Trying to find solutions online before going out and spending hours at the dealer.
I've called the dealer for a faxed document before, and they were very helpful. It didn't take long at all.
 

·
Registered
Joined
·
304 Posts
Question Re Amp

Good day,

I find that my Cruise Control 'surges' the engine.

When driving at ~120km/h, you can feel how the engine pulses, and also see that on the economy gauge.
It is quite uncomfortable, I rather drive manually.

Now, I am waiting until I have some time to take out the Amp and resolder all the connections, but I also notice that sometimes my Speedo Needle fluctuates about 5km/h up and down.

Could this have something to do with the surging?
If so, where must I look?

Regards,

Erich
 

·
Registered
Joined
·
1,547 Posts
Good day,

I find that my Cruise Control 'surges' the engine.

When driving at ~120km/h, you can feel how the engine pulses, and also see that on the economy gauge.
It is quite uncomfortable, I rather drive manually.

Now, I am waiting until I have some time to take out the Amp and resolder all the connections, but I also notice that sometimes my Speedo Needle fluctuates about 5km/h up and down.

Could this have something to do with the surging?
If so, where must I look?

Regards,

Erich
Could be your potentiometer on the throttle body
 

·
Registered
Joined
·
304 Posts
Could be your potentiometer on the throttle body

I will check it out.

However, today when I drove open road, I could monitor it.

Seems like occasionally the Speedo Needle would jump about +5km/h, and then the car would surge, so I reckon it has got more to do with the input to the Cruise Amp.

Where is the speed sender? On the Prop Shaft?

Regards,

Erich
 

·
Premium Member
Joined
·
5,924 Posts
Is your odometer working? When mine wasn't, the odo bumped on every revolution and it caused the speedo to bump, which caused the cruise to surge. Everything worked great when I replaced the odo.
 

·
Registered
Joined
·
304 Posts
Is your odometer working? When mine wasn't, the odo bumped on every revolution and it caused the speedo to bump, which caused the cruise to surge. Everything worked great when I replaced the odo.
Well, it used to work until today, when it just stopped all of a sudden.

But the Cruise Control problem was as bad when that was fine too.

Erich
 

·
Registered
Joined
·
1,547 Posts
Typically it has to do with a few things:

TPS (throttle position sensor/potentiometer), AFM/MAF (air flow sensor), and ICV (idle control sensor or valve)

Also check for any vacuum leaks from:

intake manifold, CCV/PCV crank case vent/positive crankcase vent, intake boot, and brake booster non-return or air valve.

Sometimes just a simple spray of MAF cleaner on the MAF/AFM does the trick.
But is doesn't hurt to clean out the throttle body and butterfly valve with TB cleaner as well.
 

·
Premium Member
Joined
·
10,084 Posts
I read about a 'fix' over on peachtree....they were saying to take the CC unit out of its plastic case and put it in an over for exactly ten minutes @400 degrees. You use a baking pan with foil on the bottom and then roll up some foil 'feet' to put under the CC unit. After ten minutes, turn off the oven, open the oven door and DO NOT touch the unit until it has completely cooled.

Theory being that solder flows just under 400 degrees and all your solder joints will reform. My only question is what about the rest of the components on the PCB-can they take that heat without failure? Oh well, mine's dead anyway....probably worth the gamble. Sure, it may doom your CC as a core for the rebuilders, but you can always pick another one up at a junkyard.;-)

Kevin
 

·
Registered
Joined
·
1,547 Posts
I read about a 'fix' over on peachtree....they were saying to take the CC unit out of its plastic case and put it in an over for exactly ten minutes @400 degrees. You use a baking pan with foil on the bottom and then roll up some foil 'feet' to put under the CC unit. After ten minutes, turn off the oven, open the oven door and DO NOT touch the unit until it has completely cooled.

Theory being that solder flows just under 400 degrees and all your solder joints will reform. My only question is what about the rest of the components on the PCB-can they take that heat without failure? Oh well, mine's dead anyway....probably worth the gamble. Sure, it may doom your CC as a core for the rebuilders, but you can always pick another one up at a junkyard.;-)

Kevin
It would be safer to resolder the contact points on the PCB with a soldering iron. :thumbsup:
 

·
Premium Member
Joined
·
10,084 Posts
It would be safer to resolder the contact points on the PCB with a soldering iron. :thumbsup:
Of course it would be. But many don't know the difference between a soldering gun and a soldering iron or the right temp to use to not violate the soldering foils, for example. I've seen more peeps ruin PCB's re-soldering than fix or improve them.

Kevin
 

·
Registered
Joined
·
1,547 Posts
Of course it would be. But many don't know the difference between a soldering gun and a soldering iron or the right temp to use to not violate the soldering foils, for example. I've seen more peeps ruin PCB's re-soldering than fix or improve them.

Kevin
Just a quick search furnished this site (and more):

EPE "Basic Soldering Guide"
 
1 - 20 of 36 Posts
About this Discussion
35 Replies
16 Participants
LeftCoastGeek
Mercedes-Benz Forum
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!
Full Forum Listing
Top