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  #1  
Old 03-02-2012, 11:41 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
HOW-TO: Cruise Control Amp Repair 14-pin

Hello everyone,

I decided I'd try to fix the cruise control on my 190E and 420SEL. I figured I'd write up a how-to for all of you out there. Special thanks goes out to forum member sidoog for helpful info and tips.

APPLICATION: 1987+ All Cars that uses the 14-pin VDO unit with Coding Plug.

1. TESTING THE ACTUATOR--PART A
First we must test the actuator and make sure it is within normal operating limits:

-Locate and disconnect the actuator connect inside the engine bay
-Perform the following on the actuator side of the connection

-Get an ammeter and a 2-amp battery charger.
-Connect the ammeter in series with the 12V supply
-Connect the positive probe to PIN 4
-Connect the negative probe to PIN 5

Observe the current draw. It should be within 120mA and 160mA.
The Actuator should make an audible spinning sound.

My 190E was around 130mA with my good meter. My 420SEL/560SEL measured 200mA with a cheapo meter. I blew out the fuses in the good meter before I could test the 420SEL/560SEL.

If the actuator is within this range, you can go to the next step. If not, it has the possibility of damaging the amplifier.

2. TESTING THE ACTUATOR--PART B

Next you need to test the solenoid in the actuator. This is fairly simple. Take your battery charger, and briefly tap the positive to pin 7 while maintaining ground on pin 6.

If you hear a click, then you've passed this test.

3. REPAIRING THE AMPLIFIER UNIT

If your cruise control amp looks clean and healthy (i.e no black spots indication a servo failed and hurt something) the following has a fairly high chance of success.

You'll need to open up the unit and replace a few electrolytic capacitors.



I ordered mine from Mouser.com. As long as you get a capacitor of the same capacitance and the same or higher working voltage you'll be fine. I ordered enough for 3 boards.
Here's my parts list:


The first step in replacing these is to clean off the coating VDO has on the back of the unit.

I used this varnish remover, it worked out pretty well. After it was done I took the board to the garage and used the air compressor to blow of the remains.





Here's the old and new capacitors:




All replaced!


Next Step is to re-flow the solder points. This step take quite a bit of time. Its not difficult just time consuming.

You basically want to tap the soldering iron and solder to each and every solder point on the board. Don't stay more than a few seconds. Especially on the large IC chips. They're sensitive to heat. Once you've done that you should be good to go!



On my first board I used my de-soldering iron and removed all the old solder, then re-applied new. This is a bit much as all I did on the second board was reflow the joints and it worked fine.

---------------------------------------------------------------------

Repairing 14-Pin Non Coding Plug Version ~1980-1985:


Earlier Mercedes were outfitted with these 14-pin engine/chassis specific units. They do not have a coding plug on them and as far as I can tell cannot be used on other Mercedes of the era. They do have the same pin-out as the Coding Plug variants. So testing is exactly the same.


The procedure is pretty much the same as above. Strip, Replace, Resolder.











I've not had the ability to test this unit yet as both of my 300SD's are missing their servos and mounting brackets. I have a spare servo but no good way of mounting it for testing. So tomorrow I'm going to go to the junkyard and see about finding one so I can test.



INFORMATION ON CODING PLUGS:


According to Auto Haus AZ. The coding plugs often fail before the amplifier itself. I've not experienced this yet the 420SEL, 560SEL and 190E's plugs were all intact.

Here's some pictures in case yours is bad and you need to replace the resistors.






If you have any questions or comments let me know.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Last edited by JamesDean; 03-04-2012 at 06:49 PM.
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  #2  
Old 03-03-2012, 11:26 AM
big dog 2's Avatar
ejgolfnten
 
Join Date: Feb 2005
Location: Elk Grove, Ca
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Repair

You have a lot of patience! Congrats!
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2005 Acura TL

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  #3  
Old 03-03-2012, 01:43 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
Until we got the 420SEL, I've never driven with cruise control on a Mercedes.

I think Monday I'll venture out to the junkyard and try to cobble together cruise systems for my 300SDs.

If anyone is interested, I'd be happy to repair your cruise control amp. I enjoy soldering. lol.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #4  
Old 03-03-2012, 06:59 PM
d.delano's Avatar
Dönerkebap
 
Join Date: May 2004
Location: DC
Posts: 1,466
Quote:
Originally Posted by JamesDean View Post
If anyone is interested, I'd be happy to repair your cruise control amp. I enjoy soldering. lol.
I have a sneaking suspicion that with this, you have crossed the threshold into starting a new business. You might not be aware of this yet.

You have now:
1) fixed the LCD temp readout, a perenially malfunctioning item in almost all the older MBs still on the road
2) fixed the cruise amp, another common problem

Not only have you successfully repaired these items you have shown the rest of us how. It doesn't seem like it's particle physics either! Brilliant!

There used to be a guy on the left coast who did this stuff, General Development Labs. I don't know if he does it anymore, who knows. At any rate, this kind of repair is in demand.

Next, you should try to figure out the CCU pushbutton unit! There's one for you. Although a common pattern I'm seeing is that it's those caps giving up the ghost every time.

You should throw a simple web page up and advertise repair services for this stuff. I'm sure there are a lot of units out there needing some similar repair across all makes of European autos. The electronics in these cars are ridiculously primitive, for a modern electrical engineer a cakewalk. Most people would sooner buy a rebuilt unit than replace individual components on the PCB.

I'd take you up on your offer to fix, but I've been lucky that my cruise amps have remained operational. I will however use your information to repair my LCD temperature readout. I like to solder too.
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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)
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  #5  
Old 03-03-2012, 09:29 PM
Registered User
 
Join Date: Jul 2005
Posts: 162
HVAC push button repair on Gen. I W126 would be awesome.

I bought a new one 5-6 years ago and it broke just recently. If I press the middle or second from the right button, the fan doesn't kick on. I've got to press the fourth from the left button to get the fan to kick on and then click EC or the middle button if I desire those settings.

Based on what I've read on the forums this is a common problem with the units. I got a few from the yard to try out and they all exhibited the same problem!

I've tried soldering numerous times on two different units with no success.
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  #6  
Old 03-04-2012, 04:52 AM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
I'd love to try fixing a first gen 126 climate control unit. Sadly I've got no spares to work on. The ones in my 300SD's work fine.

One forum member on here has already contacted me about fixing a unit for his 124.

I think I might head to the junkyard on Monday and get a few cruise control units and see what I can do. I dont think there are any first gen 126s at the yard though.

I probably wouldn't want nearly as much as the other places to fix these. I've seen prices up to $200+.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #7  
Old 03-04-2012, 05:03 PM
JamesDean's Avatar
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Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
I've been looking into the possibility of using the newer "with coding plug" style units on the older cars.

Here's what I've come up with:

The coding part sets the impulse per kilometer range for the unit (As evidenced by: VDO Catalog Tempostat Coding Plugs) This range differs from transmission to transmission it would appear. The VDO numbers on the two plugs I have don't match up to that image at all. I've cross referenced MB stuff a bit and came up with the following:

My 300SD uses a 722.303/722.416 transmission.

These amplifiers work in it 002 545 16 32, 002 545 82 32, 003 545 86 32.

These units also work in a variety of other chassis, namely the 201.122,
124.120
. The 190D 2.2 and the 200D/E200 Diesel respectively, both use the 722.403 transmission.

In the 190D 2.2, the amplifier was replaced by the newer 14-pin coding plug type with plug 005 545 11 32

So there is a chance that this 005-545-11-32 plug coupled with the 14-pin newer style cruise unit could be used in all 722.303/722.416 enabled cars.

I don't have this plug on hand, and its $40 from the dealer! So if anyone has this on their car. I'd love to get a peek inside at the resistors so I can order up some resistors and test this theory out!
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #8  
Old 03-04-2012, 05:25 PM
compu_85's Avatar
Waiting for his Model 3..
 
Join Date: May 2008
Location: Springfield VA
Posts: 5,174
I a picture of mine:



The bottom "resistor" is just a straight through wire.

I don't recall what number is on my plug

-J

-J
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1991 350SDL. 230,000 miles (new motor @ 150,000).

2013 Fiat 500E. 20,000 miles, 80 miles at a time.
2012 Passat TDI. 95,000 miles. More space, power, and fuel economy than the Benz
2004 Touareg V10 TDI. 150,000 miles. One of 450.
1999 Jetta TDI. 310,000 miles.
1992 Jetta ECOdiesel. 156,000 miles. 1 of 48. Sold.
1991 Jetta ECOdiesel. 430,000 miles. 1 of 700. Sold to VeeDubTDI, totaled in front of our house
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  #9  
Old 03-04-2012, 05:38 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
Quote:
Originally Posted by compu_85 View Post
I a picture of mine:



The bottom "resistor" is just a straight through wire.

I don't recall what number is on my plug
-J
Is that from your 350SDL ?
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #10  
Old 03-04-2012, 06:29 PM
compu_85's Avatar
Waiting for his Model 3..
 
Join Date: May 2008
Location: Springfield VA
Posts: 5,174
I'm 99% sure it is. It is possible it's from the 420SEL's cruise amp I got at one point, but I really don't think so.

-J
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  #11  
Old 03-04-2012, 06:48 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
Yep. Those resistors dont match up to the V8 plug I have in the first post. Must be for the 350SD/SDL's 722.361 transmission.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #12  
Old 03-04-2012, 06:51 PM
compu_85's Avatar
Waiting for his Model 3..
 
Join Date: May 2008
Location: Springfield VA
Posts: 5,174
Here's the FSM info on these cruise controls: http://www.startekinfo.com/StarTek/outside/12253/program/Chassis/54-500.pdf
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  #13  
Old 03-06-2012, 04:16 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,057
Thumbs up

Kris, you best purchase your bits from Mouser.com! My woman has been there nearly a decade... so going to Digikey is like a stab in the back to me!

I have a 1st gen unit I will mail you soon. It is a late 90s reman from Programma. The lack of low speed fan is irritating.
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I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
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Last edited by Hit Man X; 03-07-2012 at 12:56 AM.
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  #14  
Old 03-21-2012, 06:55 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,017
I found a large reference table and it looks like I can redo the coding plugs for any specific model that I need.

So far I have a 100% success rate repairing these units. I just repaired a unit for a 85 300D for 79Mercy. I've got enough spare parts to repair probably 5-6 more units if anyone is interested. Send me a PM.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

82 300SD 145k
82 300SD 265k
87 420SEL 230k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #15  
Old 03-22-2012, 12:27 AM
79Mercy's Avatar
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Join Date: Mar 2008
Location: Florida
Posts: 4,128
I got my amp back today from JamesDean my cruise control works flawlessly, used it to and from work tonight, about 20 miles each way and it held perfect constant speed the entire time. All other functions work properly, all thanks to JamesDean!
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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

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