This is my 1st post here and I would like to start by saying hello and a hugh thanks to everyone here for years of service.
I never had a need for a chilton thanks to all of you.

Ok here goes my problem keeps blowing cranking fuse the second I try to turn key to the start position.

Everything powers up. I can hear the fuel pump and injectors. Injectors seem to be much noiser now, much more than I remember. Sound like a small motor running up under the hood with a couple spitting sounds after the running motor noise quits.

I just had my tranny rebuilt due to the touque convertor crapping out. Figured might as well since I had it out and the seals were dry rotted some leakage around pump and pan I also had them tear down the transfer case inspect it and put all new seals in it.
$800 in all.

He said he replaced my neutral safety with one he had lying around not new but he said it was in way better shape than mine.

First thing a noticed that was working was a problem before I had is that I could never get my shifter out of park. So I wrapped a rubber band around actuator on the shifter under the rubber booty.

Well one good thing is that actuator is working again, as it did many year ago. I press the brake and i can hear the acculator, and I can take it out of park now.

So im guessing the neutral safety switch had someting to due with that and I figure the replacment one from the shop is good and working fine and my old one was bad.

I removed my starter and I'm still blowing crank fuse.
FYI my crank fuse is in blazer cab with driverside door open, the normal fuse block there with all the other standard fuses like radio, airbag, lamp, ect.

 

Sounds like a pinched or bare wire. That or the n safety is shorted.

 

Was up till 4 am last night popping fuses and tracing harness for a pinch wire.

Nothing really jumped out at me.
The harness looks to be undamaged its a little hard to be 100% sure.
But I can wiggle them around the bellhousing area so I'm pretty sure I didnt pinch anything.

Any suggestions on how to check if i got a short on the neutral saftey switch.

Im not that savy with electrical stuff.
I'm guessing I need to somehow find both ends of the harness with a continuity check.
The rest of the wires should be on that same connector end.
Maybe if any of them beep Im thinking then could be a short between wires.
Mabey I pinched one somehow when I tillted the motor back to get the top 2 bellhousing bolts.
I was carefull not to and it seems impossable to do theres was still alot of room so I really dont think thats it.

I did pull the tranny dip stick out from the top like an idot because I had the bellhousing loose.
I now know I should of removed it from underneath before splitting tranny from motor.
Its possible i did rub something the wrong way yanking it out i did have to really tug and twist it fought me the whole way.

I did check to see if 12 volts was making it way to chassis.
With key forward meter showed 0 voltage on frame or body so I figure no short.

I think I might wast some more fuse and try to watch the meter as i turn the key just before the fuse blows
and see if 12v appears on the truck body.
Bad thing fuse blows instantly

I can add a nano second if i up the fuse 5amps ha-ha.

 

Get a fire extinguisher and try 10A over the original rating...

 

Before I try the 20amp fuse I think I'll
Grab a new neutral safety switch on my way home from work today.
NAPA got one for $30.

I didn't know they were that cheap or I would of already replaced it.

I'll post back tonight with the results.

I'm optimistic that this will work.
But just in case if anyone want to say a prayer to your favorite deity for me. I'd appreciate it.

 

Does the fuse blow if you disconnect the transmission range switch? Will it start if you jumper the pins corresponding with the yellow and purple wires on the switch harness at the transmission?

The crank fuse actually does not directly supply voltage to the starter. Just to the starter relay which is located on the firewall. Have you tried swapping the starter relay out or testing it with it disconnected?

Here's the wiring schematic for the starter on your truck:

 

Ha-ha my truck
hip, hip, horay everyone have a drink on me.

Thanks everyone for your insight to my problem.

I had a feeling about that neutral safety switch.

Only because the tranny shop said he replaced mine with a used one he had lying around.

Also all of you who replied were verifying my hunch with your outstanding knowledge of vehicles.

And a great big THANK YOU your all the best.

Once again this sight proves to be full of genius.
gotta get some more tranny fluid and I'm cruzin again.

Why would I ever waste my cash on some dumb chilton or hanze when this sight exists.