Lights go out while towing
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Freshman User
Joined: Mar 2002
Posts: 42
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From: Spokane Valley USA
Lights go out while towing
All right, here's the deal. I have a 78' f250, 400, 4 speed custom. The problem is that the truck clearance lights go out at night while towing a trailer, the trailer also. They just flicker on and off randomly at varying intervals. They work just fine without a trailer. The head lights stay on all of the time, it is just the clearance lights. Could the trailer and truck be sucking too much juice and causing a relay to trip? Is there a relay that I am not aware of? There are no circut breaker type fuses so I am stumped. I really don't want to rewire the whole thing. Any help or insite would be greatly appreciated. Thanks.
Lead Driver
Joined: Feb 2000
Posts: 5,374
Likes: 46
From: Palm Bay, Florida
Lights go out while towing
For what I understand there is a circuit breaker built into the headlight switch itself, and if your switch is old or original I'd replace it with a new one, plus you might want to check eack light on the trailer for a short, as that would also cause an overload.
New User
Joined: Sep 2002
Posts: 12
Likes: 0
From: Curra Australia
Lights go out while towing
Before you go throwing a lot of new parts and money at it, I would suggest you do a couple of easy checks first. Does it have the same problem with every trailer you pull, or just the one? If it's OK with a different trailer, your problem is in your trailer. Have you checked for obvious bare wires in the trailer lamps? Have you checked all of the connections in the plug? When the relay in my 78 failed, I lost ALL of my lights! Spend a little time checking it out, and maybe save a few hard earned bucks.
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Senior User
Joined: Feb 2001
Posts: 153
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From: Oregon
Lights go out while towing
I am not sure if your truck has this, but I had the same problem on a 74 camper special. What I found was a park lamp relay bolted to the lower lip of the dash below the headlamp switch. Ford used this in trucks that were designed for campers or trailers. They took the park lamp wire from the headlamp switch and used it for the switch feed on another relay. then used that relay to control all of the park lamps on your truck, camper, and or trailer. By doing this they took that large load off of the headlamp switch.
hope it helps
Bushman
hope it helps
Bushman
