Hey,
Anyone give me some details on thoughts for tracking down an electrical short? I replaced the battery, but within 3 days of not using the car, its dead as a doornail. I discounted the power to the radio, glove-box light.. How should I test it? what are the specs I should see different on the volt meter ?
thanks all
The Reverend.
Full Version: Electrical Short - Battery Drains within 3 days
Try disconnecting the battery and see if it still discharges. Then you will know if it is the battery or something in the elecrtical system. How old is the battery? Also after charging does the battery cable give any spark when hooking it up? It should not.
Check that out and let us know.
Tom
Check that out and let us know.
Tom
Do you own and know how to use a multimeter? If so, (or if not) get your hands on one.
- Now disconnect the negative battery lead.
- Configure the multimeter to read amperage.
- Make sure the key is off (if you turn it on you're probably going to blow the fuse in your meter.
-Connect it in series between the negative battery cable and negative battery terminal.
- You should now see a measurement in amps. Probably pretty small if it takes 3 days.
- Start pulling fuses one at a time. Pulling one fuse is going to show a significant decrease.
- As you pull each fuse think logically about the circuit being deactivated. If it's same circuit as the clock for example, that's always going to run and pull a very small amperage. However, if you pull the one for the brake lamps, and your amperage draw decreases significantly, there's a problem here. Brake lights should pull no current, if the switch is open.
Once you find the circuit that was causing the big draw, you have narrowed down your search field. Now have a look at that circuit, for places that move. Door pass throughs, switches, etc. Keep watching your meter as you move things around. (With the fuse back in of course), watch to see that when you open the door, or move the harness around if it has an effect on you reading. Now you have the general physical location, dig in and find your short.
Keep in mind, most meters have a 10 amp fuse in them. You need to be careful not to turn on the headlights, stereo or anything that will pull more than 10 AMPs.
Good luck!
- Now disconnect the negative battery lead.
- Configure the multimeter to read amperage.
- Make sure the key is off (if you turn it on you're probably going to blow the fuse in your meter.
-Connect it in series between the negative battery cable and negative battery terminal.
- You should now see a measurement in amps. Probably pretty small if it takes 3 days.
- Start pulling fuses one at a time. Pulling one fuse is going to show a significant decrease.
- As you pull each fuse think logically about the circuit being deactivated. If it's same circuit as the clock for example, that's always going to run and pull a very small amperage. However, if you pull the one for the brake lamps, and your amperage draw decreases significantly, there's a problem here. Brake lights should pull no current, if the switch is open.
Once you find the circuit that was causing the big draw, you have narrowed down your search field. Now have a look at that circuit, for places that move. Door pass throughs, switches, etc. Keep watching your meter as you move things around. (With the fuse back in of course), watch to see that when you open the door, or move the harness around if it has an effect on you reading. Now you have the general physical location, dig in and find your short.
Keep in mind, most meters have a 10 amp fuse in them. You need to be careful not to turn on the headlights, stereo or anything that will pull more than 10 AMPs.
Good luck!
and add to the above, pull the voltage regulator to isolate a bad alternator.
a bad diode/rectifier can cause a voltage draw back through the alternator.
a bad diode/rectifier can cause a voltage draw back through the alternator.
AWESOME Step by Step.. THANK YOU.. I'll be on this tomorrow..
Do you own and know how to use a multimeter? If so, (or if not) get your hands on one.
- Now disconnect the negative battery lead.
- Configure the multimeter to read amperage.
- Make sure the key is off (if you turn it on you're probably going to blow the fuse in your meter.
-Connect it in series between the negative battery cable and negative battery terminal.
- You should now see a measurement in amps. Probably pretty small if it takes 3 days.
- Start pulling fuses one at a time. Pulling one fuse is going to show a significant decrease.
- As you pull each fuse think logically about the circuit being deactivated. If it's same circuit as the clock for example, that's always going to run and pull a very small amperage. However, if you pull the one for the brake lamps, and your amperage draw decreases significantly, there's a problem here. Brake lights should pull no current, if the switch is open.
Once you find the circuit that was causing the big draw, you have narrowed down your search field. Now have a look at that circuit, for places that move. Door pass throughs, switches, etc. Keep watching your meter as you move things around. (With the fuse back in of course), watch to see that when you open the door, or move the harness around if it has an effect on you reading. Now you have the general physical location, dig in and find your short.
Keep in mind, most meters have a 10 amp fuse in them. You need to be careful not to turn on the headlights, stereo or anything that will pull more than 10 AMPs.
Good luck!
QUOTE(jimbot2000 @ Feb 19 2012, 12:41 PM) 
Do you own and know how to use a multimeter? If so, (or if not) get your hands on one.
- Now disconnect the negative battery lead.
- Configure the multimeter to read amperage.
- Make sure the key is off (if you turn it on you're probably going to blow the fuse in your meter.
-Connect it in series between the negative battery cable and negative battery terminal.
- You should now see a measurement in amps. Probably pretty small if it takes 3 days.
- Start pulling fuses one at a time. Pulling one fuse is going to show a significant decrease.
- As you pull each fuse think logically about the circuit being deactivated. If it's same circuit as the clock for example, that's always going to run and pull a very small amperage. However, if you pull the one for the brake lamps, and your amperage draw decreases significantly, there's a problem here. Brake lights should pull no current, if the switch is open.
Once you find the circuit that was causing the big draw, you have narrowed down your search field. Now have a look at that circuit, for places that move. Door pass throughs, switches, etc. Keep watching your meter as you move things around. (With the fuse back in of course), watch to see that when you open the door, or move the harness around if it has an effect on you reading. Now you have the general physical location, dig in and find your short.
Keep in mind, most meters have a 10 amp fuse in them. You need to be careful not to turn on the headlights, stereo or anything that will pull more than 10 AMPs.
Good luck!
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