1994 E320 Cruise Control Question
 

Hello Group:

I searched the archives and didn't find a definitive answer one way or the other. My 1994 E320 has 115,000 miles and is equipped with ASR. When I bought it (15 months ago with 113,000 miles) the cruise worked about 30% of the time and has diminished to not working at all recently.

I need to know if my car has the CC amplifier that can be repaired/replaced or not. Does anyone knows for sure specifically for a 1994 E320? I noticed that FastLane lists a CC computer for a 1994 E320 sedan ($700-800). Is this the often defective amplifier?

I spoke to Peter at GDL who told me he wasn't sure if my model year used the independent system or the more complex throttle actuator system that incorporates the CC function. My car operates very well with no starting, idiling or drivability problems. If my car has the repairable CC amplifier can someone please let me know where in the car it is located.

Again, I read quite a few posts concerning CC on 1994 and 1995 E320's, but found no definitive answers on whether or not the CC system was repairable independent of the "fly-by-wire" system.

Thanks,

Derek

On your 1994 E320 has cruise control actuator is part of the idle control actuator is in one unit, I will check the brake light switch & cruise switch,and engine wireing first,check it with someone has HHT or SDS should able give you a answer.

MB STARS,

Thanks for your response.

What is HHT & SDS?

The wiring harness was replaced during the 1990's.

Thanks,

ddb

To clarify what MB STARS posted, all M104 engines, like yours, have a throttle actuator, in which three separate functions are incorporated into one part.

The throttle actuator is also called the EA / ISC / CC module:

EA - electronic accelerator
ISC - idle speed control
CC - cruise control

Usually one of the three functions fails and you are forced to replace the whole part. It cannot be fixed.

what I would check first, though, is your brake light switch. It is about a $15 part, and it can for whatever reason render the cruise control inoperable. The throttle actuator retails for about $1,400....
:eek:

Where is the brake light switch?

And how would you know that it's defective?

Brake light switch location
 

Paul, et al.,

Same question as Mcdill above. Where is the brake light switch located and how do I test it?

Also, FastLane lists a cruise control amplifier for my car. Is this a mistake? Is this not the part that GDL rebuilds?

I'm hoping it is the $15 brake light switch. But knowing my luck, it is the $1,400 part......

Thanks,

Derek

This is false. The first few years that the M104 was brought into the US (the first exmaples of which were the 1990 300SL and 1990 300CE) were CIS-E injection which used a cruise control actuator for the cruise control. They didn't have EA (Electronic Accelerator)

Right. My bad.

I generally ignore the early 3.0 liter M104 engine as it was only used on the coupes.

That's fine, but at least I've never seen the engine wiring harness disintegrate on the CIS version;)

Gilly

Just to confuse things further...
 

Just to confuse things further, my father's 1993 E320 coupe (W124 with M104 3.2 HFM) does not have electronic throttle actuation. The throttle cable runs all the way to the linkages and actuates the throttle butterfly mechanically (resulting in the heaviest throttle pedal I have ever felt, a criticism of E280 and E320 W124s here). I don't know if this is something unique to right hand drive versions or Australian versions. I have yet to see a W124 with the throttle actuator you all mention (as opposed to the cruise control actuator). I believe it has more to do with whether or not the car has ASR or not. My father's car does not have ASR. He has complained of intermittent cruise control as well. I suspect his will have a separate CC amplifier as per earlier W124s. I will have to investigate this. If this is the case then it will probably require a re-solder job as was the case with our '90 300TE which I re-soldered and repaired recently.

They could have something different in your country. I looked through my MB history disc and did find one kind of oddball (for this area) 300E with the M104 that was only made for a coupe years, including the 1993 model year, this could be the one you have experience with.
With the US version, there is a mechanical link to the throttle actuator to make the car at least "movable" (although you need to use alot of force on the pedal). Maybe that has something to do with the complaints about the HFM version of this car is it doesn't have EA.

Gilly

Interesting, but.............
 

Anyone know where my brake light switch is located and how I check it? I know my brake lights are working, but something tells me it isn't that simple. If the part is only $15 I will replace it to see if it solves my CC problem. I looked on FastLane and didn't see a brake light switch listed.

Also, why does Fastlane list a CC amplifier for a 1994 E320 sedan if these cars don't use them?

Thanks,

Derek

If I remember correctly, the brake light switch is attached to the brake pedal cluster under the dash. I removed it and cleaned the contacts to fix a surging cruise control problem a few years ago.

Thanks 944s2c, I will look for the switch tomorrow.

ddb

Good News Update
 

On the advice of the knowledgeable participants on this forum, I purchased a new brake light switch ($15.50) for my 1994 E320. This was suggetsed as a possible solution for my inoperable cruise control.

I finally got a chance this afternnoon to install the new switch. I found the old switch damaged. The plastic tab that locks the switch in place was broken off and the plastc surrounding the piston was severely cracked. Despite this, the switch was in its proper place and the brake lights operated properly.

It only took a few minutes to install the new switch. It took me 15 minutes or more to remove the plastic trim that surrounds the brake pedal. I broke this trim in several pieces due to it being very brittle. I will order a new trim piece tomorrow.

I went for a test drive and the CC operated flawlessly after not working at all for months! I would like to thank everyone for your help and suggestions. I also want to a leave a record to help others with 1994 E320 CC problems in the future.

Thanks again & have a good weekend,

Derek