Pontiac Repair: 2005 grand prix gt starting problems??, computer act, battery connections

Question
QUESTION: i have a 05 grand prix gt, v6 engine. i had the battery replaced about a couple months ago. it just recently started doing one of the following while trying to start... (the problem is intermittent):

1. key in, turn.. doors will lock, ignition kill comes on.. no start.

2. key in, turn.. headlights come on, gauges light up and go full to the right and stop... no start.

i pull the key out. i arm and disarm the alarm a couple times and try again. it repeats the above at least 3 to 4 times before finally starting.

there is no obvious pattern detected. everyone here is stumped.

help please?

thank you.

ANSWER: Hi frank:

have you had this scanned for code at one of the big box autoparts stores? if so what is set? that would be a place to start instead of taking a wild guess. I would check the battery connections first and foremost. then check the ground cable that is attached to the frame right below the battery I have seen that corrode and then you have all kinds of issues like what you stated above.  Good luck :-}


---------- FOLLOW-UP ----------

QUESTION: okay.. so .. the battery.. the ground wire... the solenoid... all tested fine. no codes either... but.. when the tech went to fire it up to return it to me the car went bazookie on him and refused to start/turn over, and the assorted electrics acted possessed. they finally got it started and said it was either the computer or the body control module, based on what had just happened.

their tech that diagnosis bcm/computer troubles wont be in til monday so i am on hold for now.

if it is the bcm, is that something they will have to replace? or is it just reprogrammed? what does a bcm for a 05 grand prix run... any idea?

thanks for the help.

Answer
I find it hard to belive it it's has acted up like it did that ther are no codes in any modules? if the body computer or the engine computer act up it like you said it should set codes in other modules. All of the onboard computers are inter connected in a network so if one of the modules decides to act up or shut down one or more of the other modules would set a code. Strange... Based on what you said I would lean more towards a body control module. that has the theft system from the factory at part of it. it is odd for a body control module to go bad on one of these cars. There is no reprogramming it. It's just set up to match the Vin# and options in the car and that's it. before one was replaced I would have the person working on it do a volatge drop test on all of the power feeds and grounds going into the module. if you have a bad connetion somewhere and it's cauing the battery volatge to be low when your trying to crank the car over it will do strange things like you mentioned. Same with the + & - battery cables just because they "look" good doens't mean they are GOOD.
good luck :-}