Q: why wont my truck start? 2002 Chevy Trailblazer

Hello. If the car was running BEFORE you replaced all of these parts, the first thing to do is make sure that you have reconnected any wiring (harnesses, plugs, grounds) that you removed when you replaced the numerous items that you have listed - including ground terminals. Also, if you did disconnect wiring for something as critical as the cam sensor, be sure that you actually have a "good" resistance free connection when you reconnect it.

It is also possible that if you connect a code scanner, it might give you output code(s) that will give you the clues you need to pinpoint the problem, particularly if a critical sensor such as the cam sensor is in fact not properly reconnected. If this doesn’t solve the problem, you can get a quick indication of whether you have a fuel delivery issue by introducing a little starter fluid in the air intake to see if you can get the engine to even briefly "run".

If it does, then you know you at least have a fuel delivery issue. You should also check for a spark (to ground) from any of the plug wires as you turn the engine over. If there is no spark, you have to diagnose the ignition system (i.e., power to coil, etc.). If you would like another expert to inspect each system before doing more repairs, a certified technician from YourMechanic can come to your car’s location to diagnose and correct the starting issue for you.