Bed marker lights and license light not working

[FoolhardyIDI]

Yesterday while I was driving, I went to turn on the lights and everything worked good for 2 seconds and then the marker lights on the bed of the truck and the license lights went out. The rest of the lights are good 's, brake light's, and cab clearance lights. I was thinking it was the head light switch so I changed that out with no luck. Yes I checked the fuses first. I pulled all the wire connections apart and put dielectric grease in all of the connections starting under the hood all the way to the back of the truck under the bed. Thinking that it might have been water that got into one of the connections. No luck at all getting the marker light's and the license light's back on.

 

[madpogue]

What "marker lights"? Is this a dually?

 

[FoolhardyIDI]

Yes it sure is. Blinkers work, headlights work, brake lights work, clearance lights work. But the marker lights on the rear fenders and license plate light don't work. I know a lot of people don't look but its in my signature. 1991 F350 Crew cab Dually

 

[79jasper]

Check the relays under the hood. May have the trailer light package.

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[FoolhardyIDI]

Ok so I have two relays that I found. I know one of them goes to the EEC and the other I have no clue. I have an option for trailer & tow and Fuel pump. My guess as these don't have electric fuel pumps it would be for the trailer & tow. Sorry night time and not much light for the pics.

 

[79jasper]

Just swap it for a known good one.

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[FoolhardyIDI]

I only have the two and they don't have the same pin type. I will get two new relays and give them a test.

 

[FoolhardyIDI]

Sweet it was a relay that was bad. Now all the lights work again

 

[79jasper]

Now keep a spare. Lol

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