My 99 chevy truck...4x4 just started giving me start troubles...everything works but starting the thing...some one told me that the computer isn't reading my key code??? the truck was crusing along until we hit a red light...then and there the moter died and i tried to start the moter and just ran down the battery....got a new battery and still no crank or anything....can you help me????

If the service 4x4 light is on, a trouble code is stored. Get the trouble code read and then you'll have a starting point for diagnostics. Real mechanics don't guess

check the ground wire to make sure it's not corroded or broken

check the socket and bulb, but that's an obvious thing to do first ; switch it from left to right and see if they work on the opposite side

No idea why anyone would change any parts,
no matter what your told,were not living in the 1960's

You need a shop to scan the vehicle for the Computer
Bus Issue

Whatever the temperature thing is about, I would not
be using it until that was resolved also

Vehicles have to be tested to find problems

Until you find a problem, there is no solution or
need for parts,is there!!

I would have the starter checked . that could drain the battery. I don't think the engine light has anything to do with the problem

The knock sensor will not cause a no-start. The knock sensor only retards the timing when the engine is running. If the starter is not working we need to check the battery voltage, battery cables, starter, engine ground, neutral safety switch, ignition switch, security system. These are the only things that can cause a no crank.
If you really have the urge to clear your computer disconnect the negative battery cable for 10 minutes.

Have you had the vehicle checked for DTC'S - diagnostic trouble codes ?.

I would start with the simplest thing and that is to check the fuses. Then return here if there is no burnt fuse

dear friend:if your battery voltage measures more than 12v it appears to be ok,but it sounds that your not getting this power threw the system,remove both the cables from the battery and clean properly replace and secure,this might solve your problem

you need to check the fuel pressure before you spend more $$ on a new regulator. it should be about 60psi give or take.
one thing you can try is to pinch off the return line and see if it runs if so its the reg.
hope this helped you out
PS the pressure gauge is about 20 to 25$ and will just screw on the fuel rail and you should have one with a bleed off so you can check flow

That is right. Could be security system. If anything fails it won't allow the vehicle to start.