Battery dies overnight, truck won't start in the morning
Every morning my battery is almost dead even though it was fine the night before. Truck cranks slow or sometimes not at all. Battery is about 8 months old. What should I check first?
Every morning my battery is almost dead even though it was fine the night before. Truck cranks slow or sometimes not at all. Battery is about 8 months old. What should I check first?
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That pattern (fine at night, dead by morning) almost always points to a parasitic draw — something staying powered on after you shut the truck off and slowly draining the battery overnight, rather than the battery itself being bad. Before replacing anything, do you have a multimeter? We can check the actual draw with the truck off.
Yeah I have one. Never tested a draw before though, how do I do it?
Disconnect the negative battery terminal, set your multimeter to DC amps, and put it in series between the negative terminal and the battery post (meter in the gap). With everything off and doors closed, a normal parasitic draw is usually under 50 milliamps. If you're seeing way more than that, start pulling fuses one at a time (with the meter still connected) until the reading drops — whichever fuse you pulled when it dropped is the circuit causing the drain.
Did this and it dropped when I pulled the cab light fuse. Dome light wasn't shutting all the way off. Replaced the door switch and it's been fine for 3 days now.