Help! No crank no start!

[Gutiman09]

Hello I’m working on my dads 1998 Sierra 5.0, I just replaced the longblock, and now it won’t start, doesn’t even crank. Followed gmc wiring diagram, and I’m not seeing 12v at the starter solenoid when the key is in the run position.
If I jump across switch side of the relay, the truck will crank. Indicating issue is on control side of relay. If I take a multimeter from b+ to the ground side of relay I see 12v indication good ground.

Seems like problem should be at the trans range switch, fuse 8 or at the ignition switch.

Ignition switch and lock cylinder have been replaced. Vehicle still not cranking.

Possibility of a security lock? The security light doesn’t stay illuminated.

Does anyone know the oem ground locations?

I’ll include picture of wiring diagrams I’ve found. Thanks for the help!

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[kolgeirr]

Do other ignition connected things work properly, like the radio, when key is On?

If yes, I hate to be that guy, but did you make sure the Crank fuse in the interior fuse block is good? I pull that fuse as an antitheft measure sometimes and this is exactly what results.

 

[pressureangle]

I always taught my students that 99% of all faults can be found with your eyes and fingers. My bet is when you find it, you'll feel silly because it's so obvious.
Start with a test light at the Crank fuse. If that's good, move to the range switch plug. If you have power in the RS plug, move to the signal hot of the starter relay. Stick the test light or have a helper run the shifter through the range and watch for light. If you have light at the switch side, suspect the relay. Don't trust a ground you tested with a DMM, use a test light. A DMM can be fooled by a circuit through some other user that powers up on the key. The Block-to-frame ground strap is in place?
Is the start wire on the S post of the starter solenoid?

 

[Gutiman09]

Do other ignition connected things work properly, like the radio, when key is On?

If yes, I hate to be that guy, but did you make sure the Crank fuse in the interior fuse block is good? I pull that fuse as an antitheft measure sometimes and this is exactly what results.

Tbh I haven’t checked that fuse.

 

[Gutiman09]

I always taught my students that 99% of all faults can be found with your eyes and fingers. My bet is when you find it, you'll feel silly because it's so obvious.
Start with a test light at the Crank fuse. If that's good, move to the range switch plug. If you have power in the RS plug, move to the signal hot of the starter relay. Stick the test light or have a helper run the shifter through the range and watch for light. If you have light at the switch side, suspect the relay. Don't trust a ground you tested with a DMM, use a test light. A DMM can be fooled by a circuit through some other user that powers up on the key. The Block-to-frame ground strap is in place?
Is the start wire on the S post of the starter solenoid?

 

[Gutiman09]

I have been testing the crank fuse under the hood with a DMM and I see 0 volts, which is why I thought the problem with further back at switch. I’ll try testing with test light tomorrow, it has a voltage indicator so I’ll be able to see both results. I will also test grounds with the test light. I have ground from battery to block, battery to frame and frame to block. & yes, I verified it’s purple in color and it only has one location it can fit. I’ll post results tomorrow. Thanks for your time

 

[Gutiman09]

Tbh I haven’t checked that fuse.

And yes all other features work like radio and instrument cluster

 

[HotWheelsBurban]

I've had that "Crank" fuse be bad on two different Suburbans. It didn't look bad, was no break in the loop like you'd normally expect to see on a blown fuse. But replaced it and was good to go.
One Burb was mine, than a year or two later, was my boss's mom's Burb (she has a '99 that's a conversion one, with low mileage because they use it only for trips). So he called me when she was going to leave his house after staying for a long weekend. "Help, you know about Suburbans, Mom went to start hers and it won't do anything".
So I told him to check that fuse, and go ahead and replace it if he had a new one. Sho nuff fixed it, so I was his favorite person for a while!

 

[Schurkey]

doesn’t even crank. Followed gmc wiring diagram, and I’m not seeing 12v at the starter solenoid when the key is in the run position.

There won't be any power at the starter solenoid "S" terminal with the key in the "Run" position. Key has to be turned all the way to "Start" to deliver power to the "S" terminal/purple wire.

If I jump across switch side of the relay, the truck will crank. Indicating issue is on control side of relay. If I take a multimeter from b+ to the ground side of relay I see 12v indication good ground.

Seems like problem should be at the trans range switch, fuse 8 or at the ignition switch.

Accurate, but not complete. Add failed relay, and problems with the wire harness connecting these items. Swapping the relay with another is the easiest way forward. And I've heard of burnt-up sockets that the relay plugs into, but more on fuel pump relays than starter relays. Do you have power at the relay B9 terminal when the key is turned to "Start"?

WHERE is the trans range switch? If it's on the transmission, maybe the harness pulled away from the trans when the engine was removed.

Ignition switch and lock cylinder have been replaced. Vehicle still not cranking.

Positioned/adjusted properly?