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Why Does a Marker or Clearance Light Only Have One Wire


I want to replace my marker, and running lights. The old ones have two green, and two white wires each. Any new ones I look at have only one black wire. What would I need to do, to replace the old lights?


Expert Reply:

The marker and clearance lights you have now ground with a single wire hence why you have two wires total, one for power and one for ground. If the marker or clearance light only has one wire then this wire is for power and the light grounds though the mounting hardware. When you determine which of the two wires you have is for power, you just simply need to cap the other one off. If the new light with only one wire is installed in a rubber grommet then you will need to run a ground wire off of the mounting hardware.

I have attached our list of clearance and marker lights for you. Please let me know if you have any further questions.

expert reply by:
Conner L

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Follow up Questions

Robert M.

I have a 1981 1ton with the 5 cab marker lights on top I went to replace them and the old lights have 3 wires the new one only has 1 and it is set into a rubber mount what is the best way to hook them up?

Etrailer Expert
Reply from Chris R.

It's hard to know how exactly those new lights would install without knowing their specific model. The single wire is certainly for power, and the assembly itself would ground through its mounting hardware. I'm not sure what you would do about the 3rd function you're needing - is it just a single function light?

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