how to trace a short..

jeepslim

New Member
Joined
Sep 16, 2007
Location
Wilmington N.C.
ok here's what I have. My cj's battery died so I replaced it. Then it died again so I replaced battery and alternator. Now it drains the battery after a couple of hours when left alone. My friend said if you unhook the positive and put the test light on the negative and it lights up that there is a short. Cant find it. Any suggestions??:confused:
 
What you've got is a drain, not a short. What your friend discribed is a short to ground and the battery would get real hot. Put a meter on amps between the positive terminal of the battery and the positive cable and start pulling fuses one at a time untill the amp draw drops. There's your problem circuit. Make sure you've got your meter on the highest setting or you might blow the fuse in it. If it drians the battery in a couple of hours it's big draw. Starter, alternator, (I know you said it's new but 90% of the ones you get from the parts stores are bad out of the box), blower motor, winch, etc. It's not got a lot of electrical consumers on it so there are only so many possibilities.

Put your hand on the alternator after charging the battery. If the diodes go bad in them, they turn into an electric motor and try to turn the engine over via the belt.
 
and to add. IF you can't track it down to a specific fuse/circuit, try unpluging the smaller lead that goes to the alt. then check your meter.
 
A real quick way is to leave the positive cable connected, disconnect the negative terminal and take the alligator clip end of your test light and hook it to the negative cable (from the car/truck) take the pointed end and touch it on the negative post of the battery, if it lights up, you've got a drain. Pull fuses and make disconnections one eat a time until the light goes out. If you have a clock or something else that has a very small draw the light will be very dim and usually pulse, this is not a drain.
 
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