Author Topic: Found some switches?  (Read 3983 times)

Dan n Lisa Lund

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Found some switches?
« on: June 15, 2015, 11:25:21 PM »
While I was working on the coach this weekend I found some switches and I am wondering what they are for. There are two push-button switches and a round diagnostic port in one picture and the other picture there is a flat rectangular diagnostic port. What are they for? All of this is under the dash right in front of the steering wheel.

Larry Dedrick

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Re: Found some switches?
« Reply #1 on: June 16, 2015, 06:28:12 PM »
Dan
         Although my coach is a 2008, the push button switches on mine, that a very similar to yours, are for ABS and Shocks. The Large plug I believe is your diagnostic for your Engine/Transmission/Chassis. The rectangular connection I am not familiar with.

                                           Remember, I Think that is what they R

              Hope this is some help.             Larry D
Laura/Larry Dedrick
Ormond Beach, FL
2008 Beaver Marq. Amethyst
Cat C15

Larry Dedrick

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Re: Found some switches?
« Reply #2 on: June 16, 2015, 06:31:39 PM »
Dan
           Also, if you follow the wire, every foot of the wire should be labeled it's purpose, as long as it's not an after-market install.

                   Larry D
Laura/Larry Dedrick
Ormond Beach, FL
2008 Beaver Marq. Amethyst
Cat C15

Keith Duner

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Re: Found some switches?
« Reply #3 on: June 16, 2015, 07:14:54 PM »
Just a little more on this subject.  It's not uncommon for vehicles of this vintage to have multiple diagnostic connectors.  Round 6 or 9 Pin or oblong 12 pin connectors are connection points for different data link protocols.  Different subsystems (transmission, engine, ABS, displays) can communicate diagnostic information on different data links (J1939, J1507/1708, J1850 or even ISO15765).  In addition to the SAE J and ISO standards, there are RPs (recommended practices) that further define implementation requirements to attempt to drive commonality.  The heavy duty industry in North America frequently uses J1939 as the comm link default standard but European OEMs have different protocols depending on whether or not the product is marketed in NA or not.  Further, if you look "under the hood" of these protocols, they are actually defined by a cluster of different SAE or ISO documents that describe in painful detail the physical layer (wires), communication protocol (code level, non destructive communication between devices, priorities....), diagnostic codes, and connector configuration of each data link. In my previous life I was involved with diagnostic tools for Allison transmission and trying to make sense of this stuff is why I am gray and bald.  Its enough to make your head explode :D