My wifes '94 Maxima (The Blue Bomber) keeps blowing out a 10A fuse. The result is that the dashboard lights go out. The 10A fuse is reportedly for the tail lights. The tail lights work fine. It takes about 2 days of driving for the fuse to blow.
My theory is that something is getting close to burning out (like a tail light), causing less resistance and therefore, higher current.
My question: should I put in a 15A fuse and burnout whatever is causing low resistance? Or is that too risky because I might fry something important?
Do the tail lights work after the fuse has blown? If they do, then the fuse in question has nothing to do with the tail lights. I wouldn’t replace it with a higher amp fuse becuase you would run the risk of a fire. My guess without knowing any more info is that a wire (most likely under the dash) is rubbing against a piece of metal somewhere and causing it to short out.
Question 1 no
Question 2 no
Read the fuse legend again, you are probably reading one fuse off (assuming the taillights still work after the “taillight” fuse blows)
The taillights work fine even with the fuse blown? You’ve misidentified the fuse.
The taillights work fine until the fuse blows, then don’t work until you replace the fuse? The circuit is properly identified. Note that the very brief description on the fuse box lid is not complete. For example, as you’ve noticed, the fused circuit for the taillights also includes the dash illumination. There may be other items in the circuit as well. To know the whole story, you need a complete definitive list of what’s connected to that fuse. There may be a list in the owner’s manual. More likely, you’ll need a good repair manual and/or wiring diagram.
The fault may lie in any item in the circuit or the positive-side wiring to any of those items. It is not in a bulb going bad (that just doesn’t blow fuses). If it were a dead short (constant), trouble-shooting would be straightforward, if tedious. Unfortunately, you have an intermittent problem, and intermittents are often the devil to find. Whatever’s causing the problem will work fine and test fine until the moment that it shorts out. Unless you’re lucky enough to catch it in the act, which is rather unlikely, your options are to visually inspect everything you can get to on the circuit in the hopes of seeing the problem, and disconnecting individual components (for several days) in the hopes of isolating it. Neither is a sure bet to produce results.
Another option is to get a 10A circuit breaker that will go in place of the fuse. Depending on the style of fuse, it may or may not be available.
Putting in a higher amp fuse is not a good idea. Either it will blow anyway, making the ploy useless, or it will allow more amperage to flow than the wiring is designed for, which could cause a fire. Nothing to gain, something to lose.
The easiest way I have found in troubleshooting this kind of problem is to rig up a 12 volt test light that you can plug into the spot where the fuse is installed. If anything is drawing power, the light bulb will illuminate. Then using a wiring diagram, I can check out the circuits and wiring to find the problem. In troubleshooting intermittant problems, I will rig up the test light with the fuse and try to duplicate the conditions that may be causing the fuse to blow.
The failure mode of a fuse often provides important clues as to the fault. A fuse that has blown through gradual overcurrent will be a clean break, with little or no evidence of charring. A fuse that has been blown by a massive overcurrent surge will die more violently, and the fuse wire will vaporise and coat the immediate vicinity in metal atoms. With a glass bodied fuse this will coat the inside surface with a burnt metallic layer. With a blade type fuse you have to look a bit more carefully.
I had an ongoing problem with my car blowing 30A fuses on the aircon circuit. Eventually I traced it to a corroded fuse contact - the contact resistance was high enough to create a significant amount of heat, and under certain circumstances this was enough to blow the fuse at well below its rating. This failure mode also left plenty of evidence - one blade of the blown fuse was always blackened and charred. This isn’t normal!
I took the fusebox apart, cleaned all the contacts with fine glasspaper and switch cleaner fluid, and bent the contact prongs in a little to provide extra mating force. I haven’t had any problems since.