Battery/alternator help

a_kelley said:
You must have threatened the electric demons enough to leave you alone... For now.

Honestly though, you'll find out if it acts back up. Any possibility that the dome lamp was left on or something like that?
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So I didn’t leave my key in the ignition and it was dead as a door nail today... guess it cane back
 
I had a radio that would kill my battery. It had power all the time for clock. Drove me crazy. The only other device that I can think of that has power all the time is the computer
 
moldman05 said:
I had a radio that would kill my battery. It had power all the time for clock. Drove me crazy. The only other device that I can think of that has power all the time is the computer
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Yea but a 13 f250 can have 20 or more computers, and most of them can power up even with the key off for different reasons. My 16 6.7 250 has the ecm, tcm, transfer case cm, air bag, abs, instrument cluster, steering column control module, drivers door module, 2 nox sensor modules, passenger door module, 2 modules for radio and I don't have the fancy Sony one, body control module, those are just the ones I can think of off the top of my head.

Do what @a_kelley said above. If the draw goes away it's the alternator, if it doesn't you're going to have to start pulling fuses til it does basically. That will narrow down which circuit it's on.
 
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Tim C said:
Yea but a 13 f250 can have 20 or more computers, and most of them can power up even with the key off for different reasons. My 16 6.7 250 has the ecm, tcm, transfer case cm, air bag, abs, instrument cluster, steering column control module, drivers door module, 2 nox sensor modules, passenger door module, 2 modules for radio and I don't have the fancy Sony one, body control module, those are just the ones I can think of off the top of my head.

Do what @a_kelley said above. If the draw goes away it's the alternator, if it doesn't you're going to have to start pulling fuses til it does basically. That will narrow down which circuit it's on.
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This. Been there many times. Also a high end diagnostic tool can let you tell the computers to power down faster. Use a jumper to hook the terminal to the battery, then hook up meter and remove jumper. If you don't, you'll blow the fuse in the meter with the in rush current. Btdt.
 
a_kelley said:
This. Been there many times. Also a high end diagnostic tool can let you tell the computers to power down faster. Use a jumper to hook the terminal to the battery, then hook up meter and remove jumper. If you don't, you'll blow the fuse in the meter with the in rush current. Btdt.
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And flip the latch in the doors while testing so the computers won't wake up because they are open and the dome lights stay off.
 
a_kelley said:
This. Been there many times. Also a high end diagnostic tool can let you tell the computers to power down faster. Use a jumper to hook the terminal to the battery, then hook up meter and remove jumper. If you don't, you'll blow the fuse in the meter with the in rush current. Btdt.
Click to expand...
Tim C said:
And flip the latch in the doors while testing so the computers won't wake up because they are open and the dome lights stay off.
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Door latch trick worked good thanks for the advice. finally took some time to figure it out. Mirror defrost relay was bad. Mirrors were hot!
Replaced it and it’s good now. Thanks guys.
 
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