i have 1995 devile.
my question is why i have to take 15 minutes to reprogramming after disconnect battery?
if not reprogramming,what will happen?
than answer back in advance

Don't know what you are talking about. Never heard of that.

my manual says:whenever i disconnect battery, my car need reprogramming,
the procedure like fellows:
runing car at parking for 10 min.
runing car at overdrive for 4 min and press the brake
running car at overdrive and turn on auto a/c for 4 min when press the brake

any idea?

I have never done that. That might be the idle learn, but it will learn on it's own.

thank you ranger

Its to relearn the idle and short term/long term fuel trim. Its not necessary to follow the procedure because it will learn on its own.

thank you fleetwood.
i have another issue:my long term fuel trim always stay under 128,most the time change from 109 to 119. my short term trim up and down around 128after warming up,before warming up short term trim goes from 80 to 101.

my question is why long term never over 128? short term can go as low as 80?
i am appreciate any help

That's nothing out of the ordinary. The computer will adjust for wear in the engine. As you add more miles onto the car you start wearing cam lobes, the timing chain stretches ect. and the computer will adjust to try and keep the engine running like it did the day it was made. You may have something like a leaky injector, which is why the computer is having to lean out the fuel mixture. It's just doing its job.

thank you very much fleet wood