Cruise control amplifier on 124 (1990 300E). - Page 2 - PeachParts Mercedes-Benz Forum

dpetryk · #16 08-23-2006, 05:13 PM

What is the question? Is it how to remove the panels or how to remove the amp?

hihosilver · #17 08-23-2006, 05:36 PM

need a address to send it to, thanks richard

kpb · #18 08-23-2006, 09:34 PM

Quote:

Originally Posted by dpetryk

What is the question? Is it how to remove the panels or how to remove the amp?

At this point the focus is the panel. Perchance once I achieve that goal, I will need direction on removing the amp itself. From what I have read in various threads, it is easier to remove the amp with the bracket attached.

Thanx.

fastpakr · #19 08-23-2006, 09:38 PM

Quote:

Originally Posted by kpb

At this point the focus is the panel. Perchance once I achieve that goal, I will need direction on removing the amp itself. From what I have read in various threads, it is easier to remove the amp with the bracket attached.

Thanx.

Grip the headlight switch tightly (by hand) and pull straight out until the knob comes off. Pull the small trim strip behind it off, and that will reveal three screws holding the top of the panel in place. Remove the trim strip over the key cylinder, and there are two screw holes there. Remove all these screws, as well as any on the lower areas of the panel (these are not hidden). Disconnect the parking brake and hood release cables, then the whole panel will drop down. Shouldn't take more than a few minutes to have the panel out.

cjlipps · #20 08-24-2006, 12:41 AM

Well, got the amp changed and that wasn't the problem. My CC does absolutely nothing and hasn't since I bought the car. Guess it's not the amp. Any other thoughts?

dpetryk · #21 08-24-2006, 06:52 AM

There are only 2 other components in the system. The switch on the steering column and the actuator itself. Both can be tested with a ohm meter if you know how to use one. Did you check the fuse?

kpb · #22 08-24-2006, 07:04 AM

Quote:

Originally Posted by fastpakr

Grip the headlight switch tightly (by hand) and pull straight out until the knob comes off. Pull the small trim strip behind it off, and that will reveal three screws holding the top of the panel in place. Remove the trim strip over the key cylinder, and there are two screw holes there. Remove all these screws, as well as any on the lower areas of the panel (these are not hidden). Disconnect the parking brake and hood release cables, then the whole panel will drop down. Shouldn't take more than a few minutes to have the panel out.

Precisely what I needed to hear -- thank you very much.

kpb · #23 08-24-2006, 07:05 AM

Quote:

Originally Posted by dpetryk

There are only 2 other components in the system. The switch on the steering column and the actuator itself. Both can be tested with a ohm meter if you know how to use one. Did you check the fuse?

I have yet to find a fuse.

cjlipps · #24 08-24-2006, 12:22 PM

Quote:

Originally Posted by dpetryk

There are only 2 other components in the system. The switch on the steering column and the actuator itself. Both can be tested with a ohm meter if you know how to use one. Did you check the fuse?

Yes, the fuse looks fine and the other components that use the same fuse are functioning properly. Guess that leaves the other two. I imagine the switch is difficult to change out? Is the actuator under the breather? I gave a cursory look last night but couldn't locate it with the breather in place. How are these tested and what should the resistance values be? Thanks for your help.

dpetryk · #25 08-24-2006, 12:54 PM

Send stuff to my company;

American Controls Corp.
6120 W. By Nw. Blvd # 180
Houston, Tx 77040
713 329-9100

dpetryk · #26 08-24-2006, 01:12 PM

The switch is not difficult just time consuming. If you are adept you can check the switch by using the ohm meter and the connections on the module connector. In fact all the ohm readings should be taken from there to insure that all the connections from these devices to the connector are intact. There are other connectors in the circuit and testing at the amp connector will rule them out. The amp connector is numbered. look on the top for the pin number assignments. The actuator is connected to the throttle linkage. You will find it underneath the air filter housing.

Now using your ohm meter check for the following;

Checking the actuator;
Pins 9 & 14 = 3k to 5k ohms (pot end to end)
Pins 9 & 13 = variable resistance from 0 to 3-5k based on the actuator position (pot wiper to one end)
Pins 13 & 14 = variable resistance from 0 to 3-5k based on the actuator position (pot wiper to the other end)
Pins 7 & 10 = low resistance 2 to 15 ohms (motor coil)

Checking the switch;
Pins 1 & 3 = < 5 ohms when switch is "on" - > 5 ohms when "off"
Pins 1 & 6 = < 5 ohms when switch is "resume" - > 5 ohms at all other times
Pins 1 & 2 = < 5 ohms when switch is "decelerate"
Pins 1 & 4 = < 5 ohms when switch is "accelerate"

Its not easy to hold the probes in place while pressing the switch a helper is usually required. When checking the pot it is wise to look for bad spots in the resistance readings. If the readings jump aroung a lot when the pot is rotated, then it is probably worn out. Its difficult to visualize this using a digital meter. Use an old style meter with a pointer is easier to see. ALso check for battery voltage when the ignition is on from pin 1 (positive) and any ground point. You should read the battery voltage. If its all there then its usually the module. The only thing left is the speed signal which the amp needs. Checking this signal requires a scope. I have never had one of those be the problem however.

dpetryk · #27 08-24-2006, 01:22 PM

Is the new module you just installed tested and verified to be good?

cjlipps · #28 08-24-2006, 02:49 PM

Quote:

Originally Posted by dpetryk

Is the new module you just installed tested and verified to be good?

No, Dave. I bought it used from a parts recycler I found through this forum and who seemed to be reliable. He said the amp I was getting was pulled from a car with credible history and that he would make it right if anything I bought from him proved to be defective. Is there some test or can I inspect the unit in some way to determine if it's good?
Question: When checking the resistance values of the switch, does it have to be held in the respective position or can it just be flipped there momentarily as in operation while driving? And, should applying the brake after activating the switch reset the reading to the before activation value?
Thank you so much for taking your valuable time to list this information for me! I really enjoy the DIY concept but with my engineering background I am a firm believer in the "Right" way to do things. Not the "If I can't fix it I'll fix it so you can't fix it" approach.

dpetryk · #29 08-24-2006, 03:10 PM

The brake has no effect on the resistance readings. You will have to hold the switch in position while checking. The amp you got from the recycler probably is suffering the same fate as all the others. However you could have problems with the switch and if the new amp is good it still wont work.

cjlipps · #30 08-24-2006, 04:53 PM

Dave, you're a big help. I'll check the switch and actuator first and address the amp issue if this one proves to be bad. Of course the ignition has to be in the run position to perform the tests? Engine on or off? When you say "pot" you mean the reading will vary with actuator position? Shouldn't it be constant with the throttle in Idle position? Sorry for the barrage of questions. I just want to get it all straight ahead of time so in case the readings are off I'll know it isn't the human element that's gone bad.
Many thanks.
Chuck.