Ford Repair: Fog lamps burned out, hella fog lights, halogen bulbs

Question
QUESTION: I replaced the Hella fog lamp bulbs (55 watt/12 Volt) on my 1978 F-100. Then when I turned the lamps on, the wiring harness to the lamps got really hot to the the touch and the bulbs faded out. Now the bulbs don't shine when turned on. Not sure what caused this....? Is there some kind of relay fuse that may have burned? Can you tell me where to start trouble shooting? Thank you!

ANSWER: I don't believe that Hella fog lights came factory/stock on a 1978 F100 so there is probably not any relays.The only fuse to look at would be whatever circuit the lights get power from.A couple of questions to ask.Did both lights,if there are only two go out at the same time before you replaced them.It is very unusual for two of anything to go bad at the same time.If the wiring harness got hot then you have a wiring problem.It could be that whatever circuit they are pulling from doesn't provide enough amperage.This happens all the time,people think that they can fix it by simply putting in a larger fuse and wind up burning up a wiring harness.The best fix and safest is to first replace the wiring harness.Go a little bit larger on you're wire size,the bigger the better.A 10-12 gauge should be sufficient enough.You will want to go with a toggle switch system,if you don't already have one.BTW,that could be you're problem also,a bad switch or faulty ground.If you are on a toggle switch to the battery the fix should be easy enough.


---------- FOLLOW-UP ----------

QUESTION: Hi James -

Thanks for your reply. Only one bulb was not shining before replecement but I replaced both for good measure. The Hella's were stock installed on my truck (bought it new in 1978 and owned it since). After I replaced both halogen bulbs and turned on the toggle switch, both bulb shown bright, the wiring behind each lamp became very hot and then the bulbs faded. Could I have installed the wrong Wattage bulb? Low and hi beams work fine. I bought two new replacement bulbs to I don't want the same to happen. Is there some kind of inline fuse I should be looking at? All was well with the fogs since 1978 until I tried to replace the Hella bulbs...(?)
Thanks again for your advice.
Andy

Answer
Being that one worked before,it does point to a wrong replacement bulb.There usually is an inline fuse.Depending if the switch is wired to the battery or to the fuse box.The fuse will be located between the power supply and the toggle switch.Happy hunting,it shouldn't be too much work,and probably is a cased in glass fuse.