running lights flash
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Joined: Aug 2015
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running lights flash
Hi I am new here and I have a 72 f-250 390 c6 2wd camper special. Turn, brake and head lights work. However I have to pull the light switch halfway out then back in a 1/16" to get running lights to come on and stay now. THEN once the headlights and running lights are on with a finnicky touch of the switch, they will stay on for a random amount of time before I can hear clicking and all the lights will begin to flash randomly on and off in no apparent order. I followed the clicking to a deal mounted on the passenger side kick board area where there are several wires plugged into some sort of relay/switch looking deal. Any ideas what it is or what the issue may be. 
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
One issue is the thermal circuit breaker in the headlight switch cycling on and off. Replace the headlight switch because of its age and inability to handle the headlight current. A way to prolong the life of the headlight switch is to install a headlight relay system that uses the headlight 'on' signal as the trigger to engage voltage directly from the battery. The best thing of all is that your headlights will be brighter due to the clean voltage source.
Removing the headlight load from the switch will like correct the other issue.'If not, then follow the same principle using relays for that circuit.
Go to the Jan 2015 update of the tech info compilation for how-tos in the electrical section.
Removing the headlight load from the switch will like correct the other issue.'If not, then follow the same principle using relays for that circuit.
Go to the Jan 2015 update of the tech info compilation for how-tos in the electrical section.
Fleet Mechanic
Joined: May 2005
Posts: 1,739
Likes: 14
From: Vale, NC
+1 to the post above. Running the relays is a pretty easy project and makes a big difference.
If you want a quick check, before you run the relays, make a 1 into 3 splice wire. Then pull the plug on the headlight switch and jump from the power source (the 1) to the slots for parking, headlight and dash lights. If everything comes on and works fine, then you know the switch is the issue and the relay you mentioned is likely not the problem.
Also, if it were me, I would run the relays first and see if that fixed it without having to replace the switch. Once the power load is off the switch it might start acting just fine. I just did this in mine and with the relays I have no problem with the switch.
Good luck.
If you want a quick check, before you run the relays, make a 1 into 3 splice wire. Then pull the plug on the headlight switch and jump from the power source (the 1) to the slots for parking, headlight and dash lights. If everything comes on and works fine, then you know the switch is the issue and the relay you mentioned is likely not the problem.
Also, if it were me, I would run the relays first and see if that fixed it without having to replace the switch. Once the power load is off the switch it might start acting just fine. I just did this in mine and with the relays I have no problem with the switch.
Good luck.
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