2005 Chevy 2500 6.0 V8 will crank but won't start

Is it automatic or manual. If it's automatic try putting it in neutral and then starting it

Connect it to a code reader scan tool. The engine light codes will tell you some of the reason, but Jeff's answer is far better than mine regarding how all this stuff works..

'Cranking' is the action of the engine spinning due to the starter motor. 'Firing' or 'starting' is what is supposed to happen after you let go of the ignition key. Many are confused by the two terms.

Is the red security light on?

Spend another load on money at a chevy dealership to get it repaired.

When you say it won't start do you mean nothing happens when turning the key car won't turn over if so then more than likely your starter is getting bad and when the starter quits spinning it probably stops on a bad spot on the brushes and looses it's connection if that's the case next time vet someone to turn the key while you take a hammer and hit the starter right on the side of the body don't hit the solonoid but if it starts right up then it's the starter going bad replace it.

Won't start how ? no crank - no start , which means when you turn the key to the start position nothing happens , starter doesn't engage. Or the starter turns the engine an it doesn't start an run. a crank - no start ?

gas? diesel? if its a 6.0 gas they have problems with the crank sensor. check for fuel pressure and spark. read the computer codes. probably crank sensor or fuel pump

Chevrolet Aveo 1,6 LS won't start just cranks crank angle sensor ok and coil ok

firing order for 5.7 v8 is 1-8-4-3-6-5-7-2 mostly all of the chevy v8s are the same firing order. the rotor button in distributer turns clockwise, the cylinder numbers are 1-3-5-7 on drivers side, 2-4-6-8 is on passengers side. To get started get your distrutor cap[new one] look on the top you will see a #1that's where you begin you must know if if rotates clockwise or counter clockwise start in that direction then follow the firing order and cylinder line up. good-day!! if cap is not marked, just pull out #1 plug, put a straw or similar in plug hole on top of piston. turn engine over by crank in front of vehicle with a wrench, when the piston comes to the very top just before it starts going down. this is tdc. and rotor button should be pointing to #1 wire on dist, cap. follow from there. good-day !!

It has nothing to do with ECU and immobiliser even if you turn your ECU OFF your car will start and will your but not properly without CPU your car will work in emergency mode. try finding Idle sensors and check them if they are ok