My wife was going to the drugstore.She was going to take the truck.It is a 2005 lariat. The battery was dead. When she went to start it ,nothing but a low hum comeing from the left front corner under the bed. When I put a lowamp charger on it it would run for 16sec then the parking lights come on for 4 secs. The low hum stops when the lights come on. Any ideas????

 

Sounds like your battery is shot.

 

Ok if I change it myself will it affect the computer??

 

No it shouldnt. When youre doing the battery unhook negative cable first when taking out and when putting new battery in connect positive cable first

 

X2

 

The hum sounds like a relay trying to energize but doesn't have enough power to do so (just a guess - but it will happen in a low voltage situation).


Changing the battery is fine. The computer will lose it's memory but will re-learn over a short period of time. There are tests such as the evaporative tests that won't complete until a few trips but you'll never notice it and unless there's an issue you would see the check engine light (which would already be on if that was the case).


Always though when removing the battery, remove ground (negative) first. When installing the new battery, install ground (negative) last. As the entire chassis is grounded, if you hook up or disconnect the positive with the ground connected you have a potential risk of shorting the battery out with a rachet or wrench when loosening/tightening. This is just a safety point.

 

I also recommend cleaning off the terminals and buying a $4 can of battery sealer when you do it too. Oh and when picking out the battery the higher the CCA the better.

 

Thanks everyone. All advise is greatly appreciated. you all have a HEALTHY and HAPPY NEW YEAR

 

Cold weather there ?
My battery started to crank slow last Winter on a really cold day...8+ years old
Replaced it w/an Interstate 850CCA this past summer