Cruise Control Question
 

Hello everyone,
I would like to report that my PanAmerican 300TD is doing great, running like a champ over all kinds of terrain. Every week I spend a few hours fixing little things here and there (T-Bracket, shifter bushings, horns...), so the time has come to order a new batch of parts for the rest of the journey. I have been thinking about replacing the cruise control computer, which I know is faulty –aren't they all at 30 years of age? ;)

http://sphotos-e.ak.fbcdn.net/hphoto...01555982_n.png

I have two problems:
1) The current cruise control computer is not the original to the car. I replaced the original faulty one with another one that also happened to be faulty. So no cigar in that aspect to check part numbers.

2) My car is a 1981 with VIN# WDBAB93A2BN004613. It's a transition year and there are two kinds of cruise control units that could fit in the car.

Which one would be the correct part number for my car?

003 545 86 32 ("Up to model year 81", according to EPC)
002 545 91 32 ("Up to model year 82", according to EPC)

Please let me know! Any help you be much appreciated!

As best I can tell this is the progression of cruise control in the 123 diesels (sedan/coupe/wagons)

005 545 12 32 (Vacuum)
001 545 79 32 (Electric)
002 545 32 32 (Electric)
002 545 91 32 (Electric)

The EPC will commonly omit the previous two from listings as they've been replaced with the 91 32.

The 003 545 86 32 wasn't seen until the mid 80's when the 300SDL came around. I dont even think it was around in 81.

Internally the 003 545 86 32 is similar in layout to the 002 545 91 32.

Strangely enough your chassis is the ONLY 123 that "got" that amplifier...Which makes it kind of suspect.

http://i.imgur.com/IPCnk.png

Here is a similar transition year car the 240D:
http://i.imgur.com/KIFQE.png

Yes, that's what I meant, sorry!
It would either be the 002 545 91 32 or the 003 545 91 32.
What's really that different about the two?

This is the cruise setup on my engine. Do you think the previous owner could have botched it? I put a 1984 computer and the actuator only worked for acceleration with the little lever at the steering column...
http://www.benzworld.org/forums/atta...c-actuator.jpg

The reason that only that model of 123 uses that amplifier is because the TD for 1981 was the first year that it was a turbo. In that year only, they used the 126 engine and transmission including the electric speed sensor instead of a cable. 1982 and later used the 123 turbo transmission.

Thank you! Well, given that my '81 300TD has a 300SD drivetrain, it must have the equivalent cruise control elements. Here is a page I found useful...

Professionally remanufactured parts with extended warranty

So, it seems like it might be the 005 545 12 32 amplifier!

Thats a cool building your parked in front of, where is that?

I got your PM as well. I'll reply here so others can see as well.

The 005 545 12 32 is a 10-pin vacuum cruise control unit. So you'll have to have a vacuum cruise unit in the engine bay.

If you've got the later servo/actuator..it'll look like my 300SD:

https://sites.google.com/site/mbcruisecontrolrepair/home/component-locations/actuator-locations

The 002 545 91 32 and 003 545 86 32 units are 14-pin units.

I suspect Mercedes might have retained the speed signal circuitry from the earlier vacuum units in your MY81 and used an amplifier that was compatible with such sensors e.g the 003 545 86 32.

So my recommendation would be to go with the 003 545 86 32 as per the MB EPC so long as you have the servo in the engine bay.

If you don't have the servo and have vacuum, I do have 005 545 12 32's (I believe..I'll have to double check) and I'm 4/4 on vacuum repairs so far!

Thanks a million! Now I can rest for tonight! :)

That's one of the historic buildings in the main square of Antigua, Guatemala!

FWIW, my '81 TD has the electric servo unit. Looks a lot like what's in your picture.

This is what I suspected. I dont know how I missed this post but I did suspect that they used a different sensor than what the rest of the 123's used.

This now makes sense since the 003 545 86 32 unit is equipped non-cable driven speedometer cars.