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1991 560 SEC
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76 Posts
Discussion Starter #1
I'm trying to install the illuminated door sills on my 91 560 SEC and I can't figure out the wiring. There is a black wire and red wire that needs to be connected. I know the red is a constant power but I don't know if the black wire should be connected to the dome light switch and if so which wire on the switch?
 

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Where did you finally end up getting your sills?
 

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1991 560 SEC
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76 Posts
Discussion Starter #3
Ebay
 

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1987 560SEC
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I would imagine it is a simple 12 volt two wire setup. Run the red wire to the door switch/dome light and the black wire to ground. I don't see why it would need a constant and a remote since there's not much juice being pulled from those little lights.

As far as determining which wire is hot when the door is opened, you are going to have to buy a meter or a test light. Try checking an auto parts store or a dollar store, they always have cheap test lights.
 

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1991 560 SEC
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Discussion Starter #5
I figured it out. The directions suck, therefore I wired the black wire from the sills to the Earth wire in the door dome light switch. Red wire went to a positive 12V wire. Sills are now working and looking sweet. Thanks
 

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Yes, dome light on the w126 is triggered by ground. But you simply wire in the black wire to the door pin switches.

Infact, from a safety view point BOTH red and black wires should be wired into the door pin switches where possible. Post 09/85 w126 models usually have 2 pin switches at each of the front doors (3 in the case of SEC's, 3rd one being for the seatbelt butler). One of the pin switches (top one) is ground and the one below is usually +12V.

Those door sill illumination strips are powered by an inverter which sends high current - you'll know if you handle the wires which actually connect to the strip !

(The dome light is also triggered by the door pin switches)

One thing to be aware of with these is not to leave the door open for a long period of time once sills are fitted. The inverter gets VERY hot and can fry. If doing work inside the car necessitates having door open for a long time (5 minutes plus) then disconnect the wire at the door pin switch. That's one reason why they should be wired up there - easy to cut power to them if required.
 
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