security light issue

i have a 1999 blazer i bought and the key always worked hard one day security light came on and now i cant start truck, i read post and replaced ignition switch --no help-- waiting for key lock cyliner to come in to see if that will fix it. does anyone have idea or no if i will have to do someing after lock is installed? clear codes/relearn key. been over two weeks messing with it and need it fixed thanks

i have a 1999 blazer i bought and the key always worked hard one day security light came on and now i cant start truck, i read post and replaced ignition switch --no help-- waiting for key lock cyliner to come in to see if that will fix it. does anyone have idea or no if i will have to do someing after lock is installed? clear codes/relearn key. been over two weeks messing with it and need it fixed thanks


First thing you need to get a engine\body capable scanner on it and get the body code no.
Post back code no.
It will point you to the problem.
Des started turn over engine?
Does engine start and run 30 seconds.
Any horn or lights flashing?
Two different security systems are used.
Do you know which one you have?
Try leaving key on for 20 minutes and see if it will over ride system.

your car has a passlock system. as crunch said scanning for (B) codes is in order. but after replacing a component in the system a relearn is nessary. by your post i assume you have done the relearn? here's some copy\paste on the relearn.

Turn ignition off. Replace failed component. With transmission in Park (A/T) or Neutral (M/T), momentarily turn ignition switch to START position (engine will not start), and then leave in RUN position. SECURITY indicator light will stay on for 10 minutes. After 10 minutes, when light turns off, turn ignition switch to OFF position for 5 seconds. Repeat step 1 twice more. Auto learn procedure will be completed during next start attempt. If VCM/PCM was replaced, reprogram VCM/PCM. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Using scan tool following scan tool manufacturer's instructions, check for DTCs. If Passlock(tm) DTCs exist, see SELF-DIAGNOSTIC SYSTEM . If engine performance-related DTCs exist, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. After repairs, check system operation. See DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.
This procedure allows relearning of BCM or VCM/PCM learned data code after replacement of BCM, sensor or VCM/PCM. DTC B3031 will set when entering programming mode.

if this does not work follow mt2500 advice get it scanned for body codes.
if you are in the area i can reflash the pcm and remove the vechicle theft deterent (vtd) if you are comfortable with deep 6ing the system.

there are no lights flashing,the secutity light just stays on ,it does start but shuts down after few seconds. after changeing ignition switch i didnt do a relearn processs will do that tomarrow while waiting for key lock cylinder.other problems happened at same time but i need to get it running before i tackle those (ex. no interior lights,rear hatch button stopped working)

Put your key in the ignition and turn it until it comes on, do not start it. leave it on for about 10 minutes and then turn it off and then try to start it. It's a GM security problem, if your key gets worn or the ignition get worn it can do that problem. Mine did it once to me and that's what I did to fix it and it's been a little over a year now and I've never had that problem ever again.
SC

i replaced key lock switch , did relearn and still wont start, during relearn security light never went out, i am recharging battery now , any more suggestions? i dont have the money right now to tow to dealer, to have them check codes,i would love to just by pass security and never have this problem again

problem fixed. after checking fuses again to see why lights were out the tbc fuse was blown under hood all lights came on and truck started right up thanks for all your help