spideyz Posted March 7, 2005 Share Posted March 7, 2005 Does anyone have an article telling how to troubleshoot a cars electrical system. I am having persistant dead battery problems after the car sits for a day or two. I guess there is a short somewhere and I remember once reading about how to check the system circuit by circuit using a test light, but I cant remember the details. Any help would be appreciated. Keith Link to comment Share on other sites More sharing options...
hooziewhatsit Posted March 7, 2005 Share Posted March 7, 2005 Here's a way to narrow down where the problem is... take an ammeter and measure the current coming out of the battery. Go to the fuse box and start pulling/replacing fuses until the current draw stops. Once you know the circuit(s) that are drawing a lot you'll have a much better idea where to start looking. good luck. If you don't have an ammeter, I'm not sure about any other ways to narrow down where your problem is. Link to comment Share on other sites More sharing options...
Petersubaru Posted March 7, 2005 Share Posted March 7, 2005 if you live near a walmart, have them test the battery(it's free if you show you are interested in buying one of there batteries) to make sure that the battery is OK( amps and voltage test) ..if your battery comes up Ok,.. then disconnect the Positive cable from your battery and take a test light or digital volt meter and bridge the positive.bat.terminal and pos. cable...position the light or meter so that when pulling/inserting each fuse one by one, you can tell if power changes, any fuse that stands out differently from the others COULD be the problem...my mechanic told me to do this as a basic step and in MOST cases you should find the problem...but at the same time is not "fool proof"...good luck Link to comment Share on other sites More sharing options...
MudisFun Posted March 8, 2005 Share Posted March 8, 2005 if you live near a walmart, have them test the battery(it's free if you show you are interested in buying one of there batteries) to make sure that the battery is OK( amps and voltage test) Just don't buy a battery from Walmart. Link to comment Share on other sites More sharing options...
rallyruss Posted March 8, 2005 Share Posted March 8, 2005 most amp meters dont read over 10 amps. keep that in mind if you decide to go that route. It is the better test method. 250 miliamps is the max you should have with all loads off. now for the test light method. as stated its not fool proof but somtimes it will lead you in the right direction. yes you will disconect a batt cable( I prefer the ground side for safety) and hook the test light in line completing the circit. test light may be on but rather dim if all is well. dim indicates that the radio or clock are pulling just a little amperage. now if you have a decent drain the light will be a bright. now you go and start pulling fuses one by one. (make sure all doors are closed) when you pull the fuse that has the load on it the light will go out or dim. look at diagram and figure out what runs off that fuse and go from there. also consider things that may not go thru the fuse box. espically thing like the alternator. bad diodes will drain a battery. they use a fusible link for the alt. out under the hood. Link to comment Share on other sites More sharing options...
Cougar Posted March 8, 2005 Share Posted March 8, 2005 While following Rallyruss's good advice be sure that everything is off in the car, like it would be parked overnight. I would be concerned if the load amperage draw is more than 80 milliamps. Usually these kind of problems can be traced to added accessories to the car or devices like a relay that get power supplied to them somehow when they shouldn't be on. Link to comment Share on other sites More sharing options...
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