# Door jamb switch wiring



## EmGee (Dec 16, 2019)

working on my 67 Lemans convertible. I have the dashcluster out, rewiring and cleaning up.
There's one, I don't understand. Please see the diagram I use. (Is it the correct one? got it from this forum)
The white wire from the door jamb, switches ground to the dome lights. 
There's a rheosplice in the wiringharness were all the whites are connected for the dome lights
With the battery connected, door open, there's ground on the white wires. With the door closed I measure 12V on the white wire. I can see it spark a bit at the rear end of the door jamb switch. Is this correct? Seems like a shortcircuit to me...allthough everything works well
With the battery disconnected, door open, there's 4Ohm resistance white wire to ground. With the door jamb closed it's open circuit.

It's a one wire doorjamb!

Thanks for the help


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## PontiacJim (Dec 29, 2012)

The wires coming off the door jam switch are ground wires, no power. It appears they tie into a junction with the dome light ground. There is a 12V power wire that goes to one side of the dome light.

What is being done is the the dome light is being powered by the 12Volt wire from the fuse block. The dome light is not grounded. It is the door jam switch that becomes the ground-to-the-body to complete the circuit when it is extended. When the door jam switch is pushed in, it breaks the ground circuit and the light goes off - but there is still 12V at one side of the dome light.

Same with the dome switch, it should be grounded so as to act as the ground circuit to complete the connection to turn on the light.


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## EmGee (Dec 16, 2019)

Thanks. I understand that. I do not understand the white wire is 12V when the door is closed. I would expect a short when the doors are opened


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## O52 (Jan 27, 2019)

You have 12 volts on the white wire because its feeding through the light bulb until you open the door, closing the switch to ground and completing the circuit. You have a small spark at the switch since it still has 12 volts on it until grounded. 
The reason it doesn't blow the fuse in either case is because the bulb acts as a load. 

If you try to ground the orange (or pink) wire from the fusebox to the bulb it will blow the fuse when grounded. In this case there is no bulb in the circuit to act as a load.


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## EmGee (Dec 16, 2019)

Thanks and that explains the low resistance of 4 Ohms I measure. (It's the bulb resistance)


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## BLK69JUDGE (Jun 10, 2010)

well posted OG52 ... holding the button in and touching it shouldnt spark


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## EmGee (Dec 16, 2019)

Well, got the cluster in again. Did the woodgrain finish and installed a tach. Also LED dashlighting and connected the battery and brake light again. 
After full install the rooftop switch failed on me. Tried to repair it, but it was too far gone.
So I decided to install new switches in the open holes left on the dash. Worked out great.
What do you think?


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