Found a tricky battery drain problem

[DaveB]

I have been fixing up my FIL's Jeep XJ and I knew the family told me it had battery issues. It sat for a few years so the battery was dead. I bought the cheapest one at Autozone and it seemed to work OK but if I let it sit for more than. a couple of days the battery would be dead. This only happened a few times and the cheap battery gave up the ghost. Luckily it was still under warranty so I bought a more expensive one. It started having the same issue. I figured there must be a drain coming from somewhere but the drain was only 5 mA when I tested it which should never kill a battery. I got thinking about what the difference must be and realized I was testing it with the hood up. So I checked the lamp that is supposed to come on when you lift the hood and found that the bulb inside was busted in half and causing it to short out and drain when the hood was closed. I didn't have a bulb to put back in so I disconnected it and that fixed the problem.

 

[Kevin B.]

I hate chasing wiring troubles, and parasitic drains are the worst. Nice job.

 

[The_Lobbster]

Good find! My Astro had a similar issue, glove box on the doghouse had a little lamp, but switch wouldn’t make great contact, causing it to stay on all the time. I just took the bulb out permanently. Tracing those battery draws will always be the death of me though.

 

[UNSTUCK]

That’s funny. I had the exact same issue not too long ago with a neighbors truck. I get to his house and the engine bay light is just hanging from the hood. I was like, “what is that”!!! - think Ace Ventura when he points to the Dolphins roster picture, instead of “who”.
Fixed it back in place and all was well with the world again.

 

[Tonkaman]

I would have never even thought of that 👍