6V light question- John Deere M

[ndgregor]

I am attempting to get the light on my John Deere M to work. It is a 6V positive ground system.

I have it wired per the schematic. Wire from rear of lamp runs to the "Lite" terminal of the switch. I assume it is grounded through the mounting bracket. However I saw some large resistance there, so in the meantime I ran a wire from the bowl of the light to the battery ground which gave me much less resistance. I do have continuity between wire connection at bulb and wire connection at switch. New bulb has been installed.

When I turn the switch to the lighting position, I do not see 6V at the light. I don't see 6V at any switch position at the light. With the tractor running, if I try to turn the lights on the whole machine begins to shut down.

I am leaning towards the switch not operating correctly at the lighting position? Would that be correct? If I tried connecting the light wire at the IGN terminal instead of the LTE terminal would that be a good way to test? Obviously the light would always be on then when running. Any help would be appreciated.

Nick

 

[The Fred]

Sounds like the light switch is shorting to earth killing the engine ignition.

 

[reb]

Is there a chance the wire you added is on the wrong connection to the light?

 

[CharlieS]

Grounds can cause a multitude of problems, and are probably the most common issue in 6/12 volt systems.
first be sure its a solid ground then make a temporary connection to the battery, straight from the light bypassing existing wiring and switch. If you have normal lamp brightness, then the problem is elsewhere. Run a temp wire to the switch and check for issues, if the problem then exists it is the switch more than likely.
Have you checked voltage on the load side of the switch?