2005 chevy colorado .Security alarm flashes when starting then stays on. Engine starts and then dies. Takes 20-30 starts to get the truck to start. How to solve the problem or disable the alarm.

Idles rough: I would check; EGR value take some starting fluid with trunk running spray engine, if the moter raises rpms you probly have a vacume leak. check fuel presure and fuel filters.change distibutor cap (orclean very good inside and out) may be some oil or someone may have leaded you pencil lead on a lead will make it mis badly.check your wires(plug).Have to go get a checker at store. gl

put gas line antifreeze.

Do you have a security light flashing in the dash when you try to start it, does the starter spin the engine for but not start it up? Have you tried spraying fuel into the intake during cranking? Do you have spark? Any fault codes? All this can be the problem and other things as well, have them all eliminated as the cause.

You need to perform a engine control module fault code test.

Security feature to prevent someone from stealing your vehicle.You are going to have to get the truck to the Chevy dealer somehow so they can reset it if you don't have the code for it.Good Luck!

honestly, any number of thing's could cause the security light to come on, i would go to my local auto store and ask them to run a coad scsnner to find the problem, good luck

when key on and engine off, does the security light flash constantly? if so its shutting down the fuel pump, it starts momentarily due to the computer priming the engine with fuel. how to reset, turn key to run position, leave it on touch nothing, takes 10-12 minutes, start watching light around 10 minutes. it will stop flashing... turn key off, then back on and start this will reset the security system. they are sensitive on this platform car it will happen again. good luck!

no you might need to replace the ignition switch

No, it can not be disabled.
The theft system is indicating a short term theft issue.
Have you added any "after market" remote start systems or alarms?
If NO.
Insert the key in the ignition, turn the key to run position ( do not start ) and leave it in that position for 10 minutes. Cycle the key to LOCK position, count to 10, then turn the key back to run position and leave on for 10 more minutes. After the 10 minutes is up, repeat the procedure (1) more time and the security system will relearn the PASS code.
Give it a try and let me know.
Regards,

I've had this problem for about a year now. When this happens, turn key to acc position and leave it for 10 minutes until the pass-lock light either stops blinking or goes out. Then turn off key and restart your truck. I have seen somewhere that if you do this 3 times consecutively, it will re-program the "brain" but I have not tried this yet. Good luck!