Hey all. 2002 f350 ext cab. Having an issue where my lights are blinking or flashing repeatedly while driving. Or whenever really. Truck running or not. Auto light switch in any position. I can hear what I believe to be the underdash circuit breaker clicking on and off. If I turn my light switch to the on position, breaker still clicks but lights remain steady.

Any ideas where to start looking? Bad wire? Bad switch?

Thanks!
Jason

 

I would check your battery connections and make sure they are all tight and no corrosion, then check the wires on the alternator and make sure that is good, follow your wire(s) from the alternator and make sure the points that they go to are all tight and any grounds are connected and tight and no corrosion. check the wires at the starter as well make sure there is no corrosion and everything is tight.

Next thing I would do is if you have a multi meter * you can pick one up cheap at harbor freight if you dont have one ) open the hood and start your truck, take your meter leads and check the voltage at the battery, you should see some slight fluctuations of the voltage which will tell you if your alternator is charging the battery.

If all is good there then it is time to check your fuses under the dash and go thru them one by one and look for any blown fuse, if you find a blown fuse write down the slot number it came from and the what size fuse it was 15, 20 etc. Go thru all the fuses there. replace any that are blown. dont start the truck yet!

Then go to the fuse box under the hood and again go thru the fuses again one by one and see if you have any fuses blown, if you find one blown write down the slot number it came from and the size of fuse, and replace it with the same size fuse. Once you have gone thru all the fuses and replaced any blown ones, then lets start the truck and see if anything is flickering still.

If you get flickering lights again, go and check the fuses that blew and see if they have blown again, if they blew again, replace them again.

Now it's time to do some detective work, check your ground wires under the hood, they will be at various points make sure they are all tight and no breaks or shorts.

My guess is that something is causing a short. One time I had a wire that was partially broken between the firewall and the engine and it was causing the problem you were experiencing, it was PITA to track down but I did find it by the process of elimination