I have been posting on other forums, and getting nowhere. So here goes. I have been having trouble with my dash lights and parking lights for some time. It all started with the dash lights flickering and going out. Then they would come back on and go off randomly, and go out for good. I thought the problem was the headlight switch, so I replaced it. The new switch was OK for a while, but it eventually did the same thing. Now, I can see that there is a problem with the truck. I replaced all of the connectors going into the headlight switch, traced the harness going to the switch until it disappeared into the main harness, replaced the switch again, and I still can't find the issue. Recently I discovered a new problem. The 15 amp fuse for the parking lights was loose in the socket. I tweaked the legs on the fuse so it would make good contact, and it was OK. I checked the power wires for continuity to ground, and have not found any shorted. All ground wires are grounded as well. I can blow the fuse for park lamps if the switch is installed and I wiggle the **** around. Sometimes there is a spark and the fuse blows. If the switch is just hanging out of the opening I cannot get the fuse to blow. I know this was a long post, but I am at my wits end. Just give me what ya got!

 

Not to short you but I had the same problem and there is plenty of info on here about it. I had a short that was causing the headlight switches to keep burning out. I think a relay also helps. Anyway do a search and I'm sure you will find your answer.

 

I will search for your posts. Thanks for the tip!

 

I think an overload is a more common cause than a short, especially on duallies. With all the extra lights a dually has, the current going through the park lamp circuit is too much for the switch and the connector terminals to handle. Installing a relay into the circuit to bypass the switch should make a big difference. Also make sure all trailer connectors installed draw park lamp current through a relay too.

 

Here is just a few and there were alot more.. have fun reading

https://www.dieseltruckresource.com/...d.php?t=209126

https://www.dieseltruckresource.com/...d.php?t=198988

https://www.dieseltruckresource.com/...d.php?t=194469

https://www.dieseltruckresource.com/...d.php?t=194079

https://www.dieseltruckresource.com/...d.php?t=192928

 

Had the same problem with our 98.5, We pull a Gooseneck trailer a lot and we got a new trailer with LED lights and havent had the problem with the switch. The park lamp circ cant handle the extra load. On our 93.5 ford had the same problem, Ford tec sugested to put in a relay very simple to do. Find the park lamp wire cut and install relay (part stores have the relay and plug for relay) Wire from switch triggers the relay , Run new power wire to relay ( fuse the power supply) and attach the wire from the lights to the relay. The relay should show wire diagram. About a 3 on a scale of 10. Good luck. ( I know I hate to cut the wire loom to but it works) New trucks have a separate circ for the trailer so they know they have a problem.

 

Had the same problem with our 98.5, We pull a Gooseneck trailer a lot and we got a new trailer with LED lights and havent had the problem with the switch. The park lamp circ cant handle the extra load. On our 93.5 ford had the same problem, Ford tec sugested to put in a relay very simple to do. Find the park lamp wire cut and install relay (part stores have the relay and plug for relay) Wire from switch triggers the relay , Run new power wire to relay ( fuse the power supply) and attach the wire from the lights to the relay. The relay should show wire diagram. About a 3 on a scale of 10. Good luck. ( I know I hate to cut the wire loom to but it works) New trucks have a separate circ for the trailer so they know they have a problem.

 

I did find that when I wiggle the park lamp fuse on the side of the dash that the lights flicker, and I can get them to go out. Now, how do I get to the back of the fuse block to investigate further?