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Crazy Electrical Issue Defies Logic

LcStrick

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Joined
April 26, 2022
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City, State
Raleigh, NC
Year, Model & Trim Level
2008 Explorer XLT
2008 Explorer.
First off, all indicators direct towards dead battery. No dome lights, no ignition lights, no headlights, no radio. Will not turn over, door locks do not work.
Connect to jump box, auto starts and runs fine. Radio reacts as if battery has died, static, lost presets. Disconnect jump box, continues to run for about five - ten minutes, then everything shuts down, dead.

Replaced battery with new, full charge. When the new, verified good battery is connected there is no change, no power. However with the new battery installed, it will start with the jump box. After running five - ten minutes it shuts down again, dead.

My confusion arises from the observation that it will start with jumper cables attached to the same cables the fully charged battery is connected to, but displays no signs of any power when the jumper cables are not attached.

Historically, this Explorer has demonstrated this behavior before, and it stopped as suddenly as it began. Last spring it began, a few days went by and it disappeared. Over the winter it did not display the problem, but now in the spring it has began again. This is not a daily driver, but with this issue the Explorer cannot be trusted to leave the driveway.

There are no codes displayed when it is running, and they all erase when the power dies.
I believe I have posted all the relevant factors, if you have any suggestions or questions I welcome them.

Thanks in advance for your insight.
 



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Sounds more like poor connections than battery.
 






^^^^ Probably. Or bad cables?
 






2008 Explorer.
First off, all indicators direct towards dead battery. No dome lights, no ignition lights, no headlights, no radio. Will not turn over, door locks do not work.
Connect to jump box, auto starts and runs fine. Radio reacts as if battery has died, static, lost presets. Disconnect jump box, continues to run for about five - ten minutes, then everything shuts down, dead.

Replaced battery with new, full charge. When the new, verified good battery is connected there is no change, no power. However with the new battery installed, it will start with the jump box. After running five - ten minutes it shuts down again, dead.

My confusion arises from the observation that it will start with jumper cables attached to the same cables the fully charged battery is connected to, but displays no signs of any power when the jumper cables are not attached.

Historically, this Explorer has demonstrated this behavior before, and it stopped as suddenly as it began. Last spring it began, a few days went by and it disappeared. Over the winter it did not display the problem, but now in the spring it has began again. This is not a daily driver, but with this issue the Explorer cannot be trusted to leave the driveway.

There are no codes displayed when it is running, and they all erase when the power dies.
I believe I have posted all the relevant factors, if you have any suggestions or questions I welcome them.

Thanks in advance for your insight.
I know you have a 4th gen, but if you have one of these big electrical connectors, maybe hit it with some electrical cleaner, check all grounds 2nd gen issues? Try this first! Does the battery actually discharge if you test it afterwards ?
 






I agree, bad connection. Use a multimeter to measure resistance between the battery terminal itself (not the connector) and the point at which you connect the jumper pack, on both the power and ground. Are you connecting the jumper pack directly to the battery ground or to some chassis ground instead?
 






I agree, bad connection. Use a multimeter to measure resistance between the battery terminal itself (not the connector) and the point at which you connect the jumper pack, on both the power and ground. Are you connecting the jumper pack directly to the battery ground or to some chassis ground instead?
Connecting directly to battery post connections. Beyond that why would it just stop running after a few minutes, completely dead, no power? My initial thought was alternator but how does it run for those few minutes if the alternator is not working and the battery is badly connected?
 






Connecting directly to battery post connections. Beyond that why would it just stop running after a few minutes, completely dead, no power? My initial thought was alternator but how does it run for those few minutes if the alternator is not working and the battery is badly connected?
it stops running? that makes me believe sometimes with fueling system... not sure specifically what though
 






The regulator/diode portion of the alternator might function until they overheat. It’s time to start ringing out the wiring with a multimeter.
 






The regulator/diode portion of the alternator might function until they overheat. It’s time to start ringing out the wiring with a multimeter.
forget my idea then ;) youre probably more right than me, simple brain hears stop running=fueling:banghead:
 






it stops running? that makes me believe sometimes with fueling system... not sure specifically what though
Yes it starts with the jump box, runs for about ten mins or so then shuts down, as if the electrical system has turned off. When it shuts down there are no "ignition lights" present, just dead. Hook the jump box back up, it starts without hesitation.
 






What’s the
forget my idea then ;) youre probably more right than me, simple brain hears stop running=fueling:banghead:
it’s always possible to have more than one issue.
 






You need to charge the battery and hook a meter to it, and see what it’s charging at idle. If it starts dropping below 12 stop it, or you’ll just kill the battery.
 






You need to charge the battery and hook a meter to it, and see what it’s charging at idle. If it starts dropping below 12 stop it, or you’ll just kill the battery.
Then check the voltage when it's running. Could be a bad alternator.
 


















That’s what I said…
what he said...if alternator was good it would keep running, and not just run for a little bit with the box
 






Connecting directly to battery post connections. Beyond that why would it just stop running after a few minutes, completely dead, no power? My initial thought was alternator but how does it run for those few minutes if the alternator is not working and the battery is badly connected?
I agree with others that a bad alternator could cause this, running for only a few minutes because during the jump start you also put some charge into the battery till the jump pack was disconnected, except for the part where you wrote "When the new, verified good battery is connected there is no change, no power".

Even with no alternator hooked up, the verified good battery (which I assume means it is fully charged?!) should have started the vehicle. One exception would be that if it were fully charged, but then put in the vehicle and left sat for several hours or more before you tried to start it, then a leaky diode in the alternator might have drained it... but then it'd read low voltage at the time of the everything-dead condition.

Maybe you do have both a bad connection, and a bad alternator.
 






I agree with others that a bad alternator could cause this, running for only a few minutes because during the jump start you also put some charge into the battery till the jump pack was disconnected, except for the part where you wrote "When the new, verified good battery is connected there is no change, no power".

Even with no alternator hooked up, the verified good battery (which I assume means it is fully charged?!) should have started the vehicle. One exception would be that if it were fully charged, but then put in the vehicle and left sat for several hours or more before you tried to start it, then a leaky diode in the alternator might have drained it... but then it'd read low voltage at the time of the everything-dead condition.

Maybe you do have both a bad connection, and a bad alternator.
Gen 3 data, should be same as his gen 4..
A bad alternator will be very obvious, goffy stuff happens in cluster etc, however...
The car will still run, I just changed the AZ RB alternator after 11 years (lifetime guarnatee), the alternator was not putting out at idle, but would charge, 14 v at 300 RPM, you can see this data by poutting hte cluter into test mode and toggling to the voltage data, or you can see that on ususal power points, or a multimeter if you don't trust your eyes with the other sources.

The fact that it runs off a jump box suggests bad connections somewhere, but he doesn't say where he's putting the jump box.

Most major parts stores will test and tell you..

Bottom line - if you only have 12volts at idle, your alternator is scrap.
 






Gen 3 data, should be same as his gen 4..
A bad alternator will be very obvious, goffy stuff happens in cluster etc, however...
The car will still run, I just changed the AZ RB alternator after 11 years (lifetime guarnatee), the alternator was not putting out at idle, but would charge, 14 v at 300 RPM, you can see this data by poutting hte cluter into test mode and toggling to the voltage data, or you can see that on ususal power points, or a multimeter if you don't trust your eyes with the other sources.

The fact that it runs off a jump box suggests bad connections somewhere, but he doesn't say where he's putting the jump box.

Most major parts stores will test and tell you..

Bottom line - if you only have 12volts at idle, your alternator is scrap.


"but he doesn't say where he's putting the jump box. If the jump clamps are on the battery outside connections seems the cable/battery connection is suspect. Another thing sometimes overlooked are the motor/ground cables. Check them out also???
 



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Gen 3 data, should be same as his gen 4..
A bad alternator will be very obvious, goffy stuff happens in cluster etc, however...
The car will still run, I just changed the AZ RB alternator after 11 years (lifetime guarnatee), the alternator was not putting out at idle, but would charge, 14 v at 300 RPM, you can see this data by poutting hte cluter into test mode and toggling to the voltage data, or you can see that on ususal power points, or a multimeter if you don't trust your eyes with the other sources.

The fact that it runs off a jump box suggests bad connections somewhere, but he doesn't say where he's putting the jump box.

Most major parts stores will test and tell you..

Bottom line - if you only have 12volts at idle, your alternator is scrap.
Or you have a bad connection.
 






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