New battery goes dead with engine shut off

RANDALL729

MEMBER
1994 LINCOLN TOWN CAR
4.6L
V8
2WD
AUTOMATIC
142,000 MILES

A few days ago I checked the alternator, stud on the underhood fuse box, and the positive battery post with the car running. The multimeter showed 14.5 volts. Today, the battery is dead. I have no courtesy lights that are on. I can't figure out what possibly could be draining the battery. The only thing that may kick on is the air suspension pump, but very rarely. I don't know where to start looking? Thank you for helping me out. RANDALL

Tuesday, July 16th, 2019 AT 4:48 PM

3 Replies

ASEMASTER6371

MECHANIC
52,796 POSTS

Good evening,

I would start by charging the battery. Then recheck, the alternator again to be sure it is still working.

https://www.2carpros.com/articles/how-to-charge-your-car-battery

Beyond that, you have a drain. I attached a guide for you to follow to narrow down the area of the drain.

https://www.2carpros.com/articles/car-battery-dead-overnight

Roy

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Tuesday, July 16th, 2019 AT 5:01 PM

RANDALL729

MEMBER
59 POSTS

Thank you very much for your expert advice. I did the test light from neg post to the neg cable. The test light showed a bright light. I took out fuses one by one. The number 17 fuse under the dash was pulled and the test light went out. You said to check the components and it narrowed the problem to be passenger side power seat switch. I ordered one. If this doesn't solve the drain, I'll continue with the other components. You wouldn't happen to know of an electrical diagram for the number 17 fuse which involves: Anti-theft, Automatic temperature control, Courtesy lamps, Key-less entry, Memory seats, Power mirrors? My Haynes manual doesn't show anything. Thank you.

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Wednesday, July 17th, 2019 AT 1:37 PM

ASEMASTER6371