no crank no start?

Hello, have you checked the underside of that fuse relay panel? They tend to corrode a lot being exposed to the elements. A lot of times the wires will eventually just break right off from the pins that the relays and fuses sit in, check that first and if it's clean in that panel we can trace the voltage drop back. Is this a 4wd and what size engine, or just give the VIN and I'll look it up from there to get the correct wiring diagrams for the whole vehicle.
Does the truck have dual batteries as well?

https://www.2carpros.com/articles/how-to-check-wiring

5.3 Vortec 4x4.

I'll check that for corrosion. also, no flashing security light.

There's no security light at all? Not even when the truck is off and locked up? This is how the fuse panel will come apart, it's very common for corrosion inside these, especially if you live in an area where they use salt on the roads during winter.
Here's your Starter circuit. Diagram 1 is the top, and the other is the lower section.
I've added the OEM diagram just to verify the wire coloring is correct.
I'm sure you have, but just make sure the battery cables are nice and tight, there's a TSB out for it.
Diagrams 6 and 7 are for the Security light and Ignition switch circuit. I think you may find low voltage to other components as well. Refresh this page to see other diagrams as I post them.
The lower dash fuse panel on the driver side is sometimes exposed to moisture or water intrusion if the door or window seals are worn (8th diagram).

Does your Check engine light come on at just the Key On?

it comes on when you first turn key then goes off.

I'll check all you have suggested and get back with you.

thanks for the help.

Okay, that's good, that means at least the ECM is powering up. If the Check engine light doesn't come on at any point, then you've lost power to the ECM or at least a section of it.

okay, i’ll be in touch.
thanks

Update: my multi meter was acting up and battery was not fully charged. i fully charged the battery and got a good functioning klein multi meter and when i checked pin 30 on starter relay i had 0 volts. I'm still going to check underneath the fuse box but i think it’s good. i had put it in when i installed the engine. Still no reverse lights except once.

if i find no problem under fuse box. Do you think it’s neutral safety switch?

It can be the Park Neutral switch, but test it first, it's a very simple circuit to test, you could actually test the PNP switch and the ECM relay control with one test using the multimeter. The PNP switch gets power from the IGN E Fuse 10-amp while the key is in the Run or Start position. 12volts are going to come from that fuse, go through the PNP switch, through the Starter Relay coil, and down the ECM. But pin 30 is the load side of the relay, not the control side, pin 30 should have power from IGN A fuse 40amp. The wiring diagrams don't show which pins on the relay are the control pins and which are the load pins, do you have a relay that has the little internal diagram on the side? The PNP switch is on the control side of the relay. So, check the ign A fuse for power. I'm not sure why GM doesn't show the pinout for the relays even on the OEM diagrams, but I think you're missing power in a different place.
The relay I'm looking at pin 30 and 87 are the load side feeding power to the Starter, and pins 85 and 86 are the control side of the relay. On the bottom of the relay there should be pin numbers too.
This is a relay I took apart but notice the pin numbers on the bottom. Check to see if you have these.
The 3rd diagram is from a 2005 Silverado, it has the pins labelled. You can see pin 87 is the pin that the ECM grounds to turn the relay on completing the pin 30 and 85 circuit and powering up the starter.

Actually, looking through this other service info, they might not have the pinout correct, but with the key On and the relay out, 2 out of the 4 pins should have 12volts. Does your relay have pinout numbers on the bottom?
Hopefully this is the correct relay you have.
Okay, finally this grey relay is an OEM Chevy Relay, pin 30 is the load, it should have power coming from the IGN A 40amp Fuse.
Sorry for the confusion there. There were a couple errors in some service information.

Disregard that 3rd wiring diagram, which looks incorrect, I'm not sure who labeled that, but it could cause a serious issue if someone tried jumping out the relay pins. I can't seem to delete it.

yes, my relay has the numbers on the bottom.

okay, i’ll check on all that and update.

thanks

update: checked fuses and ignition A 40 amp has power i ordered neutral park switch. i’ll let you know what happens once installed. i also checked under fuse box and it looked okay.

Check for 12volts at PNP switch before installing a new one, it will have 12-volts on the pink and dark green wire with the key "on" if it's working.

okay, i’ll check that before i install i’ll update once i find out.

Technically speaking, with the starter relay out, and key "on" you should have 12volts on 2 of the pins where the relay sits. Thats the fastest way to check all power inputs to the relay.

okay, thanks for input i’ll check that also.

do you know which 2 pins should be hot on starter relay?

i see the picture now. i have power at the top right pin of starter relay no power on top left side of relay. Where does that green wire go?

is that dark green wire coming from neutral safety switch?

The dark green wire is power coming through the PNP switch, if you're missing power there go to the pink wire on the Park Neutral switch and check for power there, make sure the key is on.
It should look like this. It's the pink wire on a number of different transmissions.

Okay, thanks, got it.

update: i found on the pigtail to neutral safety switch a green wire was broken and several of the other wires were frayed. I've ordered a new neutral safety switch and both pig tails to the neutral safety switch. i also found under the fuse box some of the wires on the black plug were somewhat pulled out i pushed them back in and reverse lights started working. My plan is to change the switch and pig tails. Also investigate more under black plug for pulled out wires. Hopefully it will start after all that.

update: I tested the third pin on the neutral safety switch plug like the above diagram specifies. i did have power at that pin. Since i have power there do you think it’s neutral safety switch? It’s getting power but not functioning.

Thanks for all your help I really appreciate it.

The pink wire is the 12-volt power feed, and it comes out the switch on the dark green wire labelled G. There are actually 2 pink wires I see now; one is labelled E and one is labelled C. You want to check the wires labelled E and G. The pink wire labelled E is highlighted in blue on the connector diagram. And 12volts should be coming out on the Dark Green wire. I didn't realize there were 2 Pink wires both labelled Ignition 1 voltage.

Okay, i’ll check the other pink and let you know.

If 12-volts are there, verify its coming back out on the dark green wire. Were you missing both 12-volt feeds at the relay?

update: both pink wires have power both pink wires have power going into neutral safety switch. If power is on both pink wires, then neutral safety switch must be bad? is this correct?

You have to check that power is going through the switch, it should be going in on the pink wire and coming out on the dark green wire. Thats how the circuit works, if the vehicle is not in Park or Neutral, there will be no power coming out on the dark green wire. If it is in Park or Neutral 12-volts will be coming out on the dark green wire. The dark green wire goes to the Starter Relay.

Okay, i’ve tested the dark green wire coming out of pig tail on the bigger plug on neutral safety switch no power at the dark green wire there or the dark green wire that goes to starter relay. Would this mean there is short on dark green wire, or the neutral safety switch is bad because it’s not sending power to dark green wire?

As long as the key was "on", it's not a short, it's an open circuit. You can try putting the vehicle in Neutral to and run the same test, but yes there should be power coming out on the dark green wire going to the Starter Relay. Make sure the Park Neutral switch connector is not corroded or anything, but it sounds like you have found the issue. Try moving the shifter from Park to Neutral and back to Park just to verify that it's not something in the linkage going to the PNP switch. Sometimes the linkage wears and the switch does get moved all the way into Park. The linkage to the switch should be tight.
the new switch should come with a small alignment bracket, (Positive Assurance Bracket) to make sure the switch goes on correctly, there is an alignment tool J41364 A that is used if the switch is taken off for other reasons, but a new one should come with it aligned.

Okay, i’ve done trying to wiggle shifter and in neutral. i’ve got new pigtails and a new switch ordered once i have installed i’ll post an update.

Thanks

Read my last post. There's info on aligning the new switch.

Okay, i understand that should the transmission be in neutral?

Yes, here's the instructions for replacing the switch. There are 2 different transmissions for this truck, but it's the same when replacing the Park Neutral switch. Just put some blocks under the wheels to prevent it from rolling while doing the repair.

Okay, got it, thanks.

Update: changed out neutral safety switch, truck started right up.

thanks a million for all your help.

Awesome, good news, glad you got it going. Have a good day..