"OPT" switches on Freightliner dash - what do they do??!

[petrel]

Now with a few (very few) trips under my belt, I am trying to figure out some of the systems on the truck.

The "OPT" dash switches are now vexing me! Renegade has plead the need for further research. Two Freightliner dealers haven't a clue. Nothing on trucker's report. I've even been flicking them on and off randomly to see if anything lights up, shuts-down, extends, ejects, explodes, etc! No joy.

Sorry for the lack of a close-up, but please take a look at the three switches on the end of the cluster, next to the Warning Stickers. They are all labeled "OPT", all just on/off, not momentary, and they illuminate when activated. Thanks

[superbird03]

Just guessing, but "opt" is probably short for optional. I would think you have spots on your fuse board that you could wire stuff off of that are controlled by these 3 switches. If you look at the fuse board you will probably see OPT in 3 spots but nothing wired to them.

[tgdameron]

The switch is for your use should use choose to add something requiring electrical activation.

[Bob86ZZ4]

My rig has an optional switch. The conversion builder (United Specialties) wired it to shut off the living quarters electrical. Possible one of yours is wired as such? The other optional switch on mine they wired to a set of white lights on the back. Good for hooking up the trailer with at night.

[petrel]

Originally Posted by Bob86ZZ4

My rig has an optional switch. The conversion builder (United Specialties) wired it to shut off the living quarters electrical. Possible one of yours is wired as such? The other optional switch on mine they wired to a set of white lights on the back. Good for hooking up the trailer with at night.

I've been searching for other lights and such that might be activated by them. Thanks for the suggestions.

[bushpilot]

one of my option switches illuminates some additional rear (clear) lights....but I've never figured out what one of the option switches does.

[porky69]

They are truck oem factory installed spare switches. They can be connected to pretty much anything 12volt operated. My Haulmark built 2007 Freightliner Coronado has 1 OPT switch in the dash and it is hooked to....NOTHING.


Pull the dash panel that the switches are in and look at the back of the switches and look at the wires, if there are any non-factory looking wires hooked to those switches follow them. Otherwise chances are they are available for you to use.

[bushpilot]

the "unknown" option switch in MY dash have OE/Factory wiring connected....they are not just a blank.

[porky69]

Yes they will have factory wires connected to them to supply +12volts and provide illumination but there may be 1terminal on each switch that has nothing connected. If all terminals are connected with FACTORY WIRE (has circuit numbers printed on them)then there will be a pigtail somewhere on the truck (could be near fuse panel, engine side of firewall, frame junction box, etc depending on how the chassis was speced) to hook to.
If the switch does not visually activate something the only way to figure it out is to trace wires the wires yourself or pay someone to do it for you. When I used to install truck mounted equipment it was a source of frustration as it was usually easier, cheaper and faster to install our own switches than mess with the factory stuff.