Cruise research - PeachParts Mercedes-Benz Forum

2.5Turbo · #1 07-25-2007, 02:09 AM

I did a cruise amp-ectomy to my 300D today. Very easy to get to after removing the kick panel (the one with the brake and hood releases), which was also pretty easy to remove.

It was replaced by the indy last winter. Ever since it was replaced, the cruise has been acting erratically. At certain speeds, setting the cruise will make the car gain about 5 to 8mph, and will hold the speed by repeatedly and abruptly going to near WOT and back to idle. At other speeds it will work fairly well with the accelerate/decelerate switches working correctly. At some speeds, tapping decelerate on the switch will make the car do the 5-8mph gain. At first, I was thinking actuator (before I noticed the decelerate switch was resulting in acceleration in some cases), so I bought a couple used ones and tried em, same results.

So now I'm thinking my new amplifier is defective. I discovered that the unit the indy put in was a remanufactured unit from ProgRama (www.programainc.com), with the reference resistor from the old unit installed. I tested the resistor based on the values in WIS, and it passed with values just about in the middle of the tolerances. I also took the resistor module apart and tightened the sockets a little. Reinstalled the resistor and amplifier with the same results. So the resistor is OK. The resistor socket also has the updated gray gasket.

I have not tested the switch or the speed sensor. If I get nowhere with this amp, I guess I'll have to

I'm thinking about contacting their tech support and seeing what they say, as it does have a 3 year warranty. I'm not about to open it up either because there is a warranty voiding sticker on it

Info on the reman amp:

ProgRama part#: 50532
Has the MB part # 005 545 05 32 on it
13/88 is stamped onto the metal casing just above the label

Here are some pics:

Top of amp:

Plug end with resistor installed:

Plug end with no removed (note gray gasket):

Top of resistor:

Resistor sockets:

Label with the 13/88 stamp visible at top left:

Hopefully I can get this cruise working just in time for me to go back to school

sixto · #2 07-25-2007, 02:38 AM

Are you thinking you can cruise through school?

Sixto
87 300D

2.5Turbo · #3 07-26-2007, 12:24 AM

Huh, yeah...hopefully

I shot an email off to them today...let's see what they say.

pizzachef · #4 07-26-2007, 08:13 AM

Quote:

Originally Posted by 2.5Turbo

Very easy to get to after removing the kick panel...

Can you give a brief elaboration on how you got the thing out from under the dash? I can see the one 10mm? bolt holding on the bracket that the box is screwed to, but I can't even get a socket on it because the brake pedal bracket is in the way. I'm going to look for a small 10mm box wrench...I think my regular one is too big.

Thanks for the insight.
-Geoff

EDIT - Well, I got the bolt out with a box end 10mm, 1/8 turn at a time. I opened it and it looks nice in there. I don't really know how to inspect these electronic doodads. Is there a way to test the amp?

I supposed I should test the speed sensor and other parts before messing with the amp...

2.5Turbo · #5 07-29-2007, 10:40 PM

I've been gone all weekend so I'm sorry if I didn't reply earlier. There's probably a different way of getting to it in a 123. In the 124, the removal of the kick panel (the one with the key and headlight knob) is necessary, and then it's right in front of your face.

Right now the amp is sitting in my trunk waiting for a reply from the remanufacturing company.

mcguirjf · #6 10-09-2007, 12:01 PM

Did you hear back from the mfg co?

Provided I still have my plug resistor, can I use an amplifier from any other model? For example, using an amplifier out of a 1989 300E in my 1990 300D.

Let me know!

oldiesel · #7 10-09-2007, 03:50 PM

You can use amps from several different models,just get one with the same part number stamped in the aluminum case and use your original resistor plug in. My $.02 Don

2.5Turbo · #8 10-09-2007, 10:11 PM

Quote:

Originally Posted by mcguirjf

Did you hear back from the mfg co?

Provided I still have my plug resistor, can I use an amplifier from any other model? For example, using an amplifier out of a 1989 300E in my 1990 300D.

Let me know!

Didn't hear back from them in the email. Maybe I typed my address wrong or something

. But now that I'm at school, I really can't do much with it, so I'm going to wait until thanksgiving or winter break to go any further. Will post updates when that time comes.

Between my last post and the time that I went back to school, I did some testing of my actuators, and I'm not sure which of them may be good. Might end up sending one out to GDL to have them test and rebuild if necessary after running them through their test procedures.

RUN-EM · #9 10-10-2007, 06:02 AM

If on flat or downhill the cruise "hunts" and becomes steady on slight upgrade......this is usually a sign the gears in the underhood actuator are worn. Replace or rebuild the actuator control.

Regards

Run-Em

dieseldiehard · #10 10-14-2007, 01:53 PM

Quote:

Originally Posted by 2.5Turbo

Didn't hear back from them in the email. Maybe I typed my address wrong or something

. But now that I'm at school, I really can't do much with it, so I'm going to wait until thanksgiving or winter break to go any further. Will post updates when that time comes.

Between my last post and the time that I went back to school, I did some testing of my actuators, and I'm not sure which of them may be good. Might end up sending one out to GDL to have them test and rebuild if necessary after running them through their test procedures.

The pic of the module shows it was rebuilt by Programa (or at least they placed their label on it!)
In my experience its often the actuator that is the culprit when cruise doesn't work. The resistor element in it gets worn every time you use the accelerator pedal, its constantly moving so it wears out, whether or not Cruise is "on". I believe it is a rheostat (variable resistor made with fine resistance wire) that fails but I've never torn into one of these before. Same problem occurs when the ring resistor in Nikon film cameras gets worn the light meter won't read properly. Fixing these is an expensive proposition in either case as the parts are nearly impossible to get because both VDO and Nikon use proprietary parts.
When I've sent both the actuator and electronic modules to GDL for test and evaluation, they almost always find the actuator beyond repair and then offer to sell me a new one. Mentioned something about too much involved with repairing them.
If you shop around you can find them New and selling for around $280

The same item p/n 002-545-86-32 is used in the 123 and 126 chassis but in the 603 engines the location makes it a real ***** to replace so putting in an unknown actuator would not be something I would want to do. OTOH on the 123 they are a piece of cake to replace

tobybul · #11 10-14-2007, 02:27 PM

Been following along here.......

On my 84 D, the cruise hardly works. It kicks in occassionally. Recently I noticed that if I hold down the cruise (actually more like hold up) in the activate/accelerate position, the car accelerates but drops off when I let go cruise lever.

I have always wondered if its just the electrical connections of the lever inside the steering column thats gone bad or is it the cruise module.

Any ideas?

gsxr · #12 10-15-2007, 04:53 PM

Quote:

Originally Posted by tobybul

On my 84 D, the cruise hardly works. It kicks in occassionally. Recently I noticed that if I hold down the cruise (actually more like hold up) in the activate/accelerate position, the car accelerates but drops off when I let go cruise lever.

I have always wondered if its just the electrical connections of the lever inside the steering column thats gone bad or is it the cruise module.

If the cruise won't hold (as you describe), or drops out randomly, or does weird surging... that is almost guaranteed to be a bad amplifier. The actuators on the engine are a relatively rare failure. The older amplifiers just didn't last beyond about 10 years or so. On a W124 you can score newer amps from salvage yards pretty cheap, but on a 123 I think you'll have to send it out for repair, unless you want to attempt to re-solder it... but that only works if the capacitors are still good. I upgrade my cars to the newer 016- part number amps (from salvage yards) and haven't had any trouble since.