Why is the ENG SEN fuse blowing?
10-04-2011, 05:23 PM
#21
No one said the source of a blown fuse is easy to find. Some basics: Fuses blow for 2 reasons-shorts and overloads. If it blows due to a short it USUALLY blows as soon as power is applied and you can see that little tell tale puff of black soot inside the fuse which means it go real HOT real FAST. That's a short. Overloads take more time. Something has to draw more current than the rating of the fuse and it gets hot slowly-no puff of black soot. Shorts are HOT wires touching metal where the insulation has fractured allowing the wire inside to contact the chassis(GROUND). This means the load has been bypassed. The current has found a shorter path back to the NEG side of the BATT without having to do any valueable work. With an overload some work may get done, but not productive work. The device isn't going to work very well if at all. I'd look at a schematic and unplug everything on the circuit except the most important device on that circuit. Does the fuse blow? Yes-troubleshoot that circuit. No-plug in another device and repeat till it does blow. There are tools like Fuse Saver that can substitute for fuses, but if your not a mechanic and working on these circuits regularly it's not worth the investment. There are also tools like the short finder. It's a resetable circuit breaker and a low current ameter. You substitute the circuit breaker for the fuse and move the meter along the shorted wire until the meter needle changes directions. Boom, you've found the short! You have to work fast because with shorts current is high and it isn't very long before the circuit breaker trips and you have to start over again. Good luck
