Some Trailer Lights Are Not Working But Running Lights and Marker Lights Are Not
Question:
I have hooked up all wires and my running lights,side marker lights do not light up. Tail lights work properly as do the turn signal lights. The side marker lights will work properly if hoked to a twelve volt battery only. I suspect a ground issue but the marker lights are grounded with a separate, white ground wire and directly to the frame. The tail lights are also grounded with a white wire coming from the light to the frame. What do I need to know to get my marker lights to work?
asked by: Jerry
Expert Reply:
You are probably on the right track in thinking a grounding issue is at fault. Often if a trailer has a weak or marginal ground connection it will be able to pass enough current for lower current draw lights (such as the turn signals that are not on continuously) but not enough for the always-on running and marker lights.
I suggest you recheck the security of the ground connections. You can try sanding off paint (or rust) at the spot where your ground wire ring terminals are attached. Ideally the ground will be affixed to a bare metal surface. If any of your lights use a mounting stud as the ground then you can try sanding off some paint at their mounting location to ensure metal-to-metal contact.
You can also try adding a ground jumper wire with ring terminals from the existing grounding points to another clean bare metal surface elsewhere on the trailer frame.
Check your trailer connector for any signs of even slight whitish or greenish discoloration; this can indicate corrosion that could interfere with power delivery. Follow the wiring from the trailer connector all the way back to the lights themselves to check for cracks or wear spots in the insulation that could cause a short to ground; repair or replace as necessary.
If you know the current delivery capacity of your trailer wiring harness you might compare this to the total power demand from your trailer lights. You can also check that its plug-in or hard-wire connections are secure at the vehicle. The linked article will give you additional troubleshooting guidance.
Product Page this Question was Asked From
Mighty Cord Trailer Connector Adapter - 4-Way Flat to 6-Way Round - 12" Long
- Trailer Wiring
- Wiring Adapters
- Single-Function Adapter
- 0 - 5 Feet Long
- 4 Flat
- Plug and Lead
- 6 Round
- Mighty Cord
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