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Registered
93 190E 2.6; 82 300 SD Turbo
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1,689 Posts
Discussion Starter #1
Hey everyone,

As some of you may or may not know, I've been helping people out with their cruise control systems on these 80-90s vintage cars. I figured I'd post up here too and offer.

Most of the time its an amplifier that has gone south. A fairly easy and relatively in-expensive fix.

I've got a small stock built up right now of amplifiers and am expecting a more that need repair to arrive next week. Not all of these will be applicable to your car so in that case you'd have to send the unit to me and I'll repair it and return it to you within about a week.

I've repaired just under 20 units so far and all have come back fully functional.

If you've got any questions or anything I'll be glad to help out. I can even walk you through the diagnosing if you'd like Just let me know.

-Kris
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
Joined
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4,841 Posts
Kris,

Really great of you to offer this help.

Mike
 

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Registered
93 190E 2.6; 82 300 SD Turbo
Joined
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1,689 Posts
Discussion Starter #3 (Edited)
Hey everyone, just thought I'd update this with what I've got currently for sale:

Update:

Current Units for Sale:

1 AVAILABLE - 002 545 16 32
201.024 - 190E 2.3
201.122 - 190D 2.2
126.120 - 300SD

SOLD OUT - 003 545 09 32
107.048 560SL
124.026 300E 2.6
124.028 300E 2.8
124.030 300E
201.028 190E 2.3
201.024 190E 2.3
201.034 190E 2.3-16

3 AVAILABLE - 005 545 05 32
IMPORTANT SEE NOTE AT BOTTOM
124.026 300E 2.6
124.030 300E 3.0
124.050 300CE
124.090 300TE
124.133 300D
124.193 300TD
126.024 300SE
126.025 300SEL
126.035 420SEL
126.037 500SEL
126.039 560SEL
126.044 500SEC
126.045 560SEC
126.134 350SDL
126.135 350SDL
140.134 300SD / S350
201.028 190E 2.3
201.029 190E 2.6
201.034 190E 2.3-16
201.126 190D 2.5
107.048 560SL

Note: The 005 unit has a plug that is on the back of it that is matched to a set of specific chassis so you'll either need to have your original plug or I might have on here that will work, just let me know what you need.
 

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Registered
1991 420SEL, 2001 740iL, 1989 535i
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59 Posts
I wanted to thank you for your exceptional service. :thumbsup:

Yesterday I had a longer trip to make and having cruise control working again made it a breeze.

And let's not forget: if your type is sold out Kris can always fix yours and send it back to you.

Thank you,
Wolf
 

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Registered
93 190E 2.6; 82 300 SD Turbo
Joined
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1,689 Posts
Discussion Starter #5 (Edited)
Thanks for the kind words! I figured I'd update this with my current stock thats for sale, with a picture too!

Just drop me an email ([email protected]) or a PM on here if you're interested!



1 SOON TO BE AVAILABLE - 001 545 76 32
126.032 - 380SE
126.033 - 380SEL
126.037 - 500SEL
126.043 - 500SEL
126.044 - 500SEC

1 AVAILABLE - 001 545 79 32
123.123 - 240D
123.153 - 300CD
123.133 - 300D
123.193 - 300TD

1 AVAILABLE - 002 545 32 32
123.123 - 240D
123.153 - 300CD
123.133 - 300D
123.193 - 300TD

2 AVAILABLE - 002 545 16 32
201.024 - 190E 2.3
201.122 - 190D 2.2
126.120 - 300SD

3 AVAILABLE - 005 545 05 32
REQUIRES CODING PLUG! I have some if you need one!
124.026 300E 2.6
124.030 300E 3.0
124.050 300CE
124.090 300TE
124.133 300D
124.193 300TD
126.024 300SE
126.025 300SEL
126.035 420SEL
126.037 500SEL
126.039 560SEL
126.044 500SEC
126.045 560SEC
126.134 350SDL
126.135 350SDL
140.134 300SD / S350
201.028 190E 2.3
201.029 190E 2.6
201.034 190E 2.3-16
201.126 190D 2.5
107.048 560SL
 

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Registered
1989 560 SEC (Euro)
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87 Posts
What happens when the amplifier fails?

Cruise control can fail in different ways, for example:
1. Engages normally but disengages randomly by itself
2. Won't engage from the stalk or engages intermittently
3. Engages and disengages normally but stutters or is unstable when engaged
4. Engages and disengages normally but intermittently gives the engine false signals to rapidly speed up or down (even WOT)

Which ones could be caused by the amp?
 

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Registered
93 190E 2.6; 82 300 SD Turbo
Joined
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1,689 Posts
Discussion Starter #7 (Edited)
What happens when the amplifier fails?

Cruise control can fail in different ways, for example:
1. Engages normally but disengages randomly by itself
2. Won't engage from the stalk or engages intermittently
3. Engages and disengages normally but stutters or is unstable when engaged
4. Engages and disengages normally but intermittently gives the engine false signals to rapidly speed up or down (even WOT)

Which ones could be caused by the amp?
Actually all of these are symptoms of a failing amplifier. If you're unit is engaging, even intermittently, at least one of the three major parts of the cruise control system: the stalk. The actuator can be tested to see its overall health, if this checks out ok then that leaves you with the amplifier.

How the unit operates normally:

The amplifier receives a signal that is generated in the tail shaft of the transmission. Once you hit 'accel set' this signal is stored.

The cruise control unit engages the solenoid in the actuator and it holds the throttle linkage in place. When this signal changes to a lower frequency, the cruise module will command the actuator to move the armature forward, pulling the throttle linkage with it and thus speeding up the car. Once the amp sees the signal is back to the originally set frequency it stops advancing the arm and releases it until it returns to its previous position since the linkage is spring loaded the motor doesnt have to do this work.

What goes wrong over the years?

Capacitor Aging
On the cruise control amplifier there are several energy storage devices called capacitors. These devices store the energy needed power the circuitry, engage the solenoid, and move the armature. These devices have a limited amount of life in them when compared to the other components on the board. They have a life rated in the hours 2,000 hours @ 105C is fairly common. Other capacitors on the board are rated for 300,000 hours @ 105 C and will last probably longer than the car itself.

When you have these capacitors age, they loose their ability to hold charge and thus make it difficult to perform necessary operations like power the chips that monitor and compare speed signals. It makes it especially difficult to send current to the motor to move arm and solenoid. That's where you get most of the intermittent behavior.

I've heard some people say that the Germans also had quality problems with their capacitors. I've seen a few different brand capacitors used over the years so there might be some evidence to support this. Additionally, my one 300SD, which was purchased new in 1982 had a repair order in 1983 for a replacement cruise control amplifier. The bill would have been $450 (in today's money). My grandparents never went through with it and thus the car never had cruise really. I removed the board from the car and performed my normal repair routine. Worked perfectly.

Cold Solder Joints
The second problem comes from cold solder joints. Solder connects all the points on the board. I've been told that solder can have a life span of about 20 years or so before it starts to show signs of failure like cold solder joints. The cruise control boards are partially coated with a special type of polyurethane coating. This helps prevent moisture and other outside elements from oxidizing and corroding solder points. Several boards I've worked on have failed to come back to life after a simple capacitor replacement. They needed a full-on resolder of every point on the board to come back to life.

Actuator Failure
This type of failure is actually rare. I've worked on 35+ cruise control units now and none of them have had any signs of actuator failure.

The actuator has a motor and solenoid inside of it. As the motor ages and wears it will start to draw more current from the cruise control amplifier. If this current reaches a suitable high level it can cause damage to the amplifier rendering it inoperable. The output transistors--the devices responsible for supplying power to the motor--are rated up to 4 amps. The actuator should draw an maximum of 220mA or so. Anything higher, say near 250mA and you should consider sourcing a used one. Most of the actuators I've seen draw between 120-220mA. I don't see a problem with that range. Once you get rather high numbers well beyond 250mA the transistors will heat up, they'll start to draw lots of power on the circuit board, this will cause everything to heat up. Some parts of the board are not designed to handle this and they break down and well that's the end of the amplifier!

For information about testing your actuator, see my post here:
http://www.peachparts.com/shopforum/2913150-post5.html

Other Problems

Poor/Bad Speed Signal
This would be more common in 123/124/201 chassis cards with a mechanically driven speedometer. In these cars the tailshaft gear train drives a cable that reaches up to the back of the instrument cluster. This drives the speedometer. There is a small unit attached to the speedometer that converts the mechanical signal to electrical. This unit can go bad, although I've not experienced or heard of it really. I only know of the one that was in my early test bench setup that failed (largely due to my curiosity at its inner workings).

In 126 chassis cars, there is a device on the transmission that converts the mechanical movement of the gear train into electrical signal. From there a wire carries it up to a connector located just to the right of the accelerator pedal, then up into the instrument cluster and off to the cruise control unit. I've not encountered any units that have failed. Only issues with wiring at that connector next to the pedal and that was an isolated incident with my friends 560SEL (it was pretty beat up).

Low System Voltage
If the car's overall voltage falls to below 10 or so volts. The cruise control system will disable. The newer style units may work a little longer than the older ones at this lower voltage however, if you're under 10V you've got bigger fish to fry than the cruise control.

I hope this answered your questions. The short answer is really capacitors and cold solder joints. If you've got anymore questions, please feel free to ask. I'd be more than happy to answer them.

If you're interested in one of the units or a repair for one that's not listed, drop me an [email protected] or drop me a PM on here.

-Kris
 

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Registered
One Smoke Silver '87 570SEC, one Black Pearl '87 560SEL
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4,533 Posts
Kris,
I have a batch of maybe a half dozen probably not good cruise amps just sitting on a shelf. If you want them, they're yours. PM me an address.

Mike
Las Vegas
 

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Registered
93 190E 2.6; 82 300 SD Turbo
Joined
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1,689 Posts
Discussion Starter #10
Kris,
I have a batch of maybe a half dozen probably not good cruise amps just sitting on a shelf. If you want them, they're yours. PM me an address.

Mike
Las Vegas
PM sent Mike, Thanks!
 

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Registered
93 190E 2.6; 82 300 SD Turbo
Joined
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1,689 Posts
Discussion Starter #11
Another inventory update. I'll try to keep these to once every two weeks or so. Just drop me an email ([email protected]) or a PM on here if you're interested!

1 AVAILABLE - 001 545 76 32
126.032 - 380SE
126.033 - 380SEL
126.037 - 500SEL
126.043 - 500SEL
126.044 - 500SEC

1 AVAILABLE - 001 545 79 32
123.123 - 240D
123.153 - 300CD
123.133 - 300D
123.193 - 300TD

2 AVAILABLE - 002 545 16 32
201.024 - 190E 2.3
201.122 - 190D 2.2
126.120 - 300SD

1 AVAILABLE - 003 545 09 32
107.048 - 560SL
124.026 - 300E 2.6
124.028 - 300E 2.8
124.030 - 300E
201.028 - 190E 2.3
201.024 - 190E 2.3
201.034 - 190E 2.3-16

4 AVAILABLE - 005 545 05 32
REQUIRES CODING PLUG! I have some if you need one!
124.026 - 300E 2.6
124.030 - 300E 3.0
124.050 - 300CE
124.090 - 300TE
124.133 - 300D
124.193 - 300TD
126.024 - 300SE
126.025 - 300SEL
126.035 - 420SEL
126.037 - 500SEL
126.039 - 560SEL
126.044 - 500SEC
126.045 - 560SEC
126.134 - 350SDL
126.135 - 350SDL
140.134 - 300SD / S350
201.028 - 190E 2.3
201.029 - 190E 2.6
201.034 - 190E 2.3-16
201.126 - 190D 2.5
107.048 - 560SL
129.061 - 300SL
129.066 - 500SL
 

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Registered
93 190E 2.6; 82 300 SD Turbo
Joined
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1,689 Posts
Discussion Starter #12
Another inventory update. I'll try to keep these to once every two weeks or so. Just drop me an email ([email protected]) or a PM on here if you're interested!

1 AVAILABLE - 001 545 76 32
126.032 - 380SE
126.033 - 380SEL
126.037 - 500SEL
126.043 - 500SEL
126.044 - 500SEC

1 AVAILABLE - 002 545 16 32
201.024 - 190E 2.3
201.122 - 190D 2.2
126.120 - 300SD

1 AVAILABLE - 003 545 09 32
107.048 - 560SL
124.026 - 300E 2.6
124.028 - 300E 2.8
124.030 - 300E
201.028 - 190E 2.3
201.024 - 190E 2.3
201.034 - 190E 2.3-16

2 AVAILABLE - 005 545 05 32
REQUIRES CODING PLUG! I have some if you need one!
124.026 - 300E 2.6
124.030 - 300E 3.0
124.050 - 300CE
124.090 - 300TE
124.133 - 300D
124.193 - 300TD
126.024 - 300SE
126.025 - 300SEL
126.035 - 420SEL
126.037 - 500SEL
126.039 - 560SEL
126.044 - 500SEC
126.045 - 560SEC
126.134 - 350SDL
126.135 - 350SDL
140.134 - 300SD / S350
201.028 - 190E 2.3
201.029 - 190E 2.6
201.034 - 190E 2.3-16
201.126 - 190D 2.5
107.048 - 560SL
129.061 - 300SL
129.066 - 500SL
 

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Moderator
1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
Joined
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5,187 Posts
Thanks man for doing this invaluable service... Sounds great!

Mine in the '87 SEC does the damndest thing .. intermittently when engagING the cruise the car will accelerate on its own with NO letup 'til the cruise disengaged.. It can & will do this repeatedly some days and then after a period of driving will remain normal in every way.. This phenomena is the only aberrant behavior the cruise displays...

I am hoping its the solder joints as I have touched up a dozen or so points that appeared crystalized or the pin ringed by a tiny crack in the solder when viewed with a strong magnifier...

I'll put the amp back in and give it a try..

Keep up your good work there!

Cheers, MBL
 

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Registered
93 190E 2.6; 82 300 SD Turbo
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1,689 Posts
Discussion Starter #14
Hey MBL,

I'm always glad to help out fellow enthusiasts!

I actually had the same thing happen to me once when I was testing a unit. It was an 005 545 05 32 and I needed to get more solder from the store. So I figured I'd throw it in the 190E and see how it performed. I'd only replaced the capacitors at this point so I was curious. Well I engaged it and it never let go! I thought it would eventually stop but I got to 70mph (set at 50/55) and it was still going. I got home and re-soldered the entire board and that cured the problem. It was nice and smooth from there on out.

Best of luck in your repairs! Let me know if you need anything or have any questions!
 

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Registered
93 190E 2.6; 82 300 SD Turbo
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1,689 Posts
Discussion Starter #16
Just thought I'd update this again. It has been a while! I've got the following available right now, if you don't see your car on the lists please feel free to email ([email protected]) or PM me and I'll see what we can to do help you out!

1 AVAILABLE - 001 545 76 32
126.032 - 380SE
126.033 - 380SEL
126.037 - 500SEL
126.043 - 500SEL
126.044 - 500SEC

1 AVAILABLE - 002 545 16 32
201.024 - 190E 2.3
201.122 - 190D 2.2
126.120 - 300SD

1 AVAILABLE - 004 545 24 32
124.193 - 300TD
124.133 - 300D
201.126 - 190D 2.5

2 AVAILABLE - 005 545 05 32
REQUIRES CODING PLUG! I have some if you need one!
124.026 - 300E 2.6
124.030 - 300E 3.0
124.050 - 300CE
124.090 - 300TE
124.133 - 300D
124.193 - 300TD
126.024 - 300SE
126.025 - 300SEL
126.035 - 420SEL
126.037 - 500SEL
126.039 - 560SEL
126.044 - 500SEC
126.045 - 560SEC
126.134 - 350SDL
126.135 - 350SDL
140.134 - 300SD / S350
201.028 - 190E 2.3
201.029 - 190E 2.6
201.034 - 190E 2.3-16
201.126 - 190D 2.5
107.048 - 560SL
129.061 - 300SL
129.066 - 500SL
 

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560 SEC
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100 Posts
Haha, I had that in my 560 SEC a few times.. Flick the cruise control on and it took off, I was in 60mph traffic the first time and sh*t myself... Second time it happend I was on a clear open road, flicked it on, it droped down a gear and it literally kept going and going until I touched the brake pedal.. Fast cars these... :thumbsup:

Edit, I would fix it myself, iv replaced tiny components on toyota sc300 digi dash's, but I'm breaking my euro 560 now, as this is your thing thought you might be interested in the amp to fix, give me a pm if you want to buy it.
 

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Registered
1988 300SE W126
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60 Posts
Hi Kris,

I own a 1988 300SE 126.024 Australian model. Most of the time my cruise control doesn't work. When it does it only works for a short time before it goes to sleep again. Because it only works for a short time I haven't noticed it wanting to keep increasing the speed like some people have described. I am prety handy with a soldering iron and would have a go at repairing my amplifier. I have a few questions if you don't mind.

1. Where is the amplifier located? I believe it is behind the carpeted panel up above but near the steering column.

2. If I can repair mine would I need the coding plug you mention?

3. What do I look at next if repairing the amplifier doesn't make any difference, or it didn't need repairing?

4. How much are you selling your repaired amplifiers for with a coding plug?

5. Do you sell on an exchange basis? If not my I suggest this as a way for you to keep some stock on hand.

Thanks for your help and regards,
Neil
 

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Registered
93 190E 2.6; 82 300 SD Turbo
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1,689 Posts
Discussion Starter #19
Hi Kris,

I own a 1988 300SE 126.024 Australian model. Most of the time my cruise control doesn't work. When it does it only works for a short time before it goes to sleep again. Because it only works for a short time I haven't noticed it wanting to keep increasing the speed like some people have described. I am prety handy with a soldering iron and would have a go at repairing my amplifier. I have a few questions if you don't mind.
It looks like your 300SE was either equipped with an 003 545 07 32 or 003 545 09 32 (if you have 3.07 differential) or an 005 545 05 32 coding plug type unit with either 005 545 09 32 (if 3.07 differential) or 005 545 10 32 plug installed on the unit.


1. Where is the amplifier located? I believe it is behind the carpeted panel up above but near the steering column.
On the 124 it is located just to the left of the steering column if you remove that knee panel.

2. If I can repair mine would I need the coding plug you mention?
Nope, not in the least. The coding plug is for 005, 014 and 023 model number amplifiers. If you were to change your amplifier to an 005 style and did not have a plug then you would need one. If you've got an 003 545 09 32 or something else that naturally does not have a coding plug you will not need one.

3. What do I look at next if repairing the amplifier doesn't make any difference, or it didn't need repairing?
Well since your cruise does partially work, it might be a safe bet to assume that your actuator and cruise control stalk are working fine as if they were not your cruise would not do anything at all! In addition to any soldering work you do I would recommend replacing all the electrolytic capacitors on your cruise unit.

4. How much are you selling your repaired amplifiers for with a coding plug?
My price is $60 USD plus shipping out to you for both coding type and non-coding type amplifiers. I normally ask that you return me your old non-working unit as well.

5. Do you sell on an exchange basis? If not my I suggest this as a way for you to keep some stock on hand.
I normally sell on a core basis, that is, you buy one off me and return your old unit so that I might fix it and continue helping other enthusiasts. In the past I purchased a bunch of cruise amplifiers (some 40) and I still have some of those thanks to the cores.

Thanks for your help and regards,
Neil
You're welcome! If you need any help at all let me know

Here is a link to my cruise control diagnostics, you might find something helpful in there:
PeachParts Mercedes ShopForum - View Single Post - Cruise Control Amplifier Diagnostics & Amplifier Repair
 

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Registered
1988 300SE W126
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60 Posts
Hi Kris,

Thanks for your reply.

At the risk of appearing pedantic my car is a 126 not a 124. Maybe you just made a typo. I would think that the amplifier is however in the same place on both. I would also think that the part number would be on the amplifier, but given that my VIN starts with 126.024 wouldn't that indicate I would need a 005 545 05 32 as per your list of available units?

Regards,
Neil
 
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