Help Reading a Wiring Diagram

[George7941]

This is the wiring diagram for a Freightliner truck for an optional dash mounted switch controlling the box interior lights. The problem is that the terminal numbering on the switch is totally different from the numbering in the diagram.

The switch itself is a two position switch, OFF and ON, with no intermediate position. Pins 8/10 and 7/9 are for leds, no problems there. Multimeter testing of the disconnected switch shows two SPDT (sub)switches in it (SPDT meaning A-B switch OFF, A-C switch ON). Looking at pins 1,2 and 3, which ones are C, NO and NC?

Switches are normally displayed in the OFF position. The diagram seems to indicate the switch is ON.

 

[Colt45ws]

I think its mislabeled. The LED on the left is probably illumination and the one on the right turns on when the switch is turned on. Im gonna say pin 2 is C, 1 is NC and 3 is NO.

 

[bullwinkle]

SPDT means single pole (control or lever), double throw (controls TWO internal switches)-looks like only 1/2 of the switch is being used?

 

[Colt45ws]

This diagram is totally messed up, btw. It looks like it was drawn as a three position switch for some reason then brought into MS Paint and the line was added from the middle pole to the "None" postion to make it a two position. Seriously, look at how different the lines are between the two. How blocky the one on the right is. I think somebody goofed and did a half-butt fix.

 

[zzyzzx]

You really need to rotate that schematic. It's too hard to read that way.

 

[George7941]

Originally Posted By: bullwinkle
SPDT means single pole (control or lever), double throw (controls TWO internal switches)-looks like only 1/2 of the switch is being used?


Two internal switches is Double Pole (two different circuits being switched).

Yes, only half of the switch is being used.

 

[George7941]

As Colt45Ws pointed out, 2 C, 1 NC and 3 NO is what it is supposed to be when I look at the complete diagram. 2 is fed 12v, 1 is not used and 3 goes to the lights.

The NONE label is really misleading and Freightliner should have 1 and 3 labeled NC and NO and that would avoid any confusion.