2005 Pontiac bonneville gxp will crank sometimes. security light stays on can't get it to go off. Will crank after playing with lock. plz help

Well, since the SECURITY light is staying on, you obviously have a theft deterrent problem.....I assume this is PKIII......

There was a TSB about the ring around the lock cylinder coming loose and moving out of place, causing intermittent problems......not sure if that is your problem......typical code readers and scan tools can't read B codes.......

I removed your other post since it was about the same issue, having one thread will help you get assistance easier.

Are you able to have a dealer scan that to see what code you are getting?
There should be some code returned if the security light is staying on, as Gus said though, regular scanners won't work, most likely you are going to need to see a dealer.

i had same problem in my monte carlo until it one day would not turn over.check your key it should have a resistor near plastic top.if you can feel it raised with fingernail scratching across it then your wire on the switch is probably broken.you can take an ohm meter and set it to 10 ohm or if you have a meter that reads auto like a fluke or good one,put key in vice or have someone hold it steADY AND TOUCH ONE LEAD TO ONE SIDE AND THE OTHER ON OTHER SIDE.try to not let it wiggle.you will probably get somewhere between 12000 to maybe 3000.i followed the yellow wire down from steering and inside the one wire is two wires that hook to a connector,that runs on to a box that sends resistance to let ignition and fuel pump work.if you have a newer spare key try this key and see if it works every time.if it does you can match the resistance with a few resistors soldered between the wires at the first connection that un-plugs.leave couple inches of wire off of end on the two wires inside yellow wire,soldedr the resistors between the two and your good to go.remember you are in the thousands and hundreds range so you have to be within about 10 or 13 hundreds.clean inside switch with cotton swab at top inside switch,just to make sure no crud.if i can give you more info i gladly will.my e-mail should show,if not its randrews612@gmail.com

sorry i cut in on that post like that.im not sure how it happened.i apologize

if the newer key works every time and light goes off its the key,if not you can save youself possibly a bundle instead of new switch and having the key programmed.ace can cut you one and program it if they will.not all places can or will.usually 75 to 100 dollars.this resistance tecnique will not hurt anything.you can take a multi-pak from radioshack and hand twist them together and put between wires until you match resistance inside the plus or minus 10 range and when you get it light will go off and it will crank up

sorry ni think you have one year newer and not the vats system.if it is really nice car you will probably want to get dealer to fix with probably new switch,otherwise there is another way but you have to have a toggle with bypass switch,cut yellow and white wires in bundle from steering colum,and wrap each partially around key switch ring.it will work,but you have a little messy looking set-up.sorry

Rob, you are all over the place......I believe this is PKIII.....

Gus is right, if it were PK II that might help Rob, but most likely since it is a Bonneville after 99' it is most likely PK III, which uses a rfid transponder, no resistor pellet.

If it doesn't have the pellet in the key, here is something that may help get it started so you can get it to a dealer to look at it.
It is the "PassLock Re-Learn" procedure.

How to start your late model GM vehicle with a flashing SECURITY or THEFT SYSTEM light

Sorry I am not able to help more, I don't know as much about PK III as PK II.