2008 Berkshire Cruise Control

[silver]

Originally Posted by Herk7769

I found some posts on a trucking site (Freightliner) that might help:

Find the air system manifold. On this manifold there are 5 or 6 switches that look like automotive oil pressure sending units. These could be your problem. They're $9 a piece and I've dealt with a truck that didn't have cruise going down the highway but did parked and I've also dealt with a truck that had an audible air leak. Replacing these switches fixed those problems.


Another suggestion had to do with the speed sensors; there are two. One is dedicated to the speed control and the other to the speedometer. Swapping the wires on them may help isolate the problem.


Brake pedal switch; If the pedal is not returning all the way up for some reason, the speed control will be locked out.

Another suggested grounding cables between cab and frame could be corroded and you could be losing your ground connection.

Hope these help you troubleshoot ...

Good info. I found the switches. There are two under the coach below the Brake peddle. One for the front breaks and one for the back. Have not found the speed sensors. May need to call Freightliner again.

Thanks

[silver]

Originally Posted by retasker

Well, except for the typo "38QS"

It is actually a 390QS.

I also have a 39QS. Is the connector on the back of the Freightliner Display? How did you remove it?

[retasker]

Actually there are two connectors. And, yes, they are on the back of the display module. The easiest way to remove them is to remove the allen-head screws holding the whole dash assembly and then lift the assembly to get to the back of the display. The connectors each have a tab that must be depressed to unplug them.

Alternately you can stand on your head under the steering wheel and try to get to the connectors from the back - which I found to be way too hard.

As far as the internal connectors, I don't remember exactly how to disassemble the display module, but it is possible to do so if you are careful. I am an electrical engineer so I have done this sort of thing before and have experience with the various connector types.

Hopefully you will not have to disassemble the whole unit.

[retasker]

Did you ever solve your speed control problem?

MY module has started acting strangely lately. The low brake pressure warning beep goes on when the gauges show plenty of pressure and then goes off by itself. Sometimes when I start the engine none of the displays work but if I restart they come on just fine. Any idea where to get info or help or a replacement for this module?

[I-RV]

Silver
Daimler has a web site where after you have registered, you enter your moho serial number and it will show all the chassis parts and wiring. The web site is at.........
http://www.dtnaconnect.com/
To view their EZWIRING, your computer must have the CGM viewer installed and the site offers it to be installed.

I found that there is a problem, wherein the Daimler site does not like the Microsoft Edge browser for EZWIRING. Upon running my old Explorer browser, I got into EZWIRING. The cruise control wiring for my 2012 is attached. I hope that it helps you.
Hank

[accumack]

Silver, there was an issue with some Freightliner cruise controls, and there was a recall for some diodes that I think weren't installed correctly (loose). You might check those they are under the dash.

[silver]

Originally Posted by retasker

Did you ever solve your speed control problem?

MY module has started acting strangely lately. The low brake pressure warning beep goes on when the gauges show plenty of pressure and then goes off by itself. Sometimes when I start the engine none of the displays work but if I restart they come on just fine. Any idea where to get info or help or a replacement for this module?

I have heard some people have had this issue and it has been related to a bad ignition switch. Some have had the switch replaced. Don't know if this might be happening to you.