2011 Tahoe no crank no start need help

[Rockman101]

Small update... Found a bad wire drivers side by the transmission. Yellow with black stripe. Corroded bad from rubbing. Ran out of time to fix it. Probably have time tomorrow

 

[Rockman101]

Fixed the wire didn't fix the problem, but I checked my ignition wire under column while cranking it drops to 0 volts. When I let off back to 12.5 volts? Red with white stripe wire. So something is pulling down the network??!!

 

[mikez71]

You can crank it with the scanner, but not the key?

Bad ignition switch?

 

[Rockman101]

You can crank it with the scanner, but not the key?

Bad ignition switch?

Yup scanner cranks it. Turn key nothing. It is a new ignition switch, but maybe bad out of the box. It's a gm part not a cheapy

 

[j91z28d1]

Fixed the wire didn't fix the problem, but I checked my ignition wire under column while cranking it drops to 0 volts. When I let off back to 12.5 volts? Red with white stripe wire. So something is pulling down the network??!!

do you know where that wire is getting it's 12v from? I'd guess a fuse? I'm not in front of my software to take a look. but I've heard of fuses getting bad connections in the fuse box, soon as they get a load it drops off?

 

[Rockman101]

do you know where that wire is getting it's 12v from? I'd guess a fuse? I'm not in front of my software to take a look. but I've heard of fuses getting bad connections in the fuse box, soon as they get a load it drops off?

Good idea, I'll give it a check

 

[j91z28d1]

Fixed the wire didn't fix the problem, but I checked my ignition wire under column while cranking it drops to 0 volts. When I let off back to 12.5 volts? Red with white stripe wire. So something is pulling down the network??!!

so I looked back at the ign switch diagram. I'll upload.

I look at these diagrams kinda often and I'm not really sure what's going on here. so first that red wire with a white strip. if this is right, fuse 35 from under hood box 2amp. constant power to the ign switch and theft module. I don't believe you should see power drop off it while in acc, run or start.

looking at the ign diagram the right side, I'm not sure what all is going on. maybe some other guys can see it better. white wire pin 6 is 5v from the bcm. pink/black is the ign control/command to the bcm, but key in switch is there too. so looks to me like key in but off position it sends 12v to the pink/black. once moved to run it connects the 5v white wire to the pinkblack and then when moved to start it connects the 5v thru a resistor to the pink/black. dropping 5v to 3v maybe?

I'm mildly confused by why it's doing that or if I'm seeing something incorrect. but either way, I say all that but check for 12v at fuse 35 under the hood while in start and see what happens. if you keep 12v move to pin 4 of the ign switch and look for 12v while trying to start there.

the rest of the linked internal switches. acc and run it sends 12v to theft; yellow pin 2, transferr case; blue pin 10, tranny; blue pin 9, and ecm; blue pin 18 of connector X1


in run and start it sends 12v on pink to bcm so the bcm knows to turn on the run/crank relay under hood.

 

[Rockman101]

so I looked back at the ign switch diagram. I'll upload.

I look at these diagrams kinda often and I'm not really sure what's going on here. so first that red wire with a white strip. if this is right, fuse 35 from under hood box 2amp. constant power to the ign switch and theft module. I don't believe you should see power drop off it while in acc, run or start.

looking at the ign diagram the right side, I'm not sure what all is going on. maybe some other guys can see it better. white wire pin 6 is 5v from the bcm. pink/black is the ign control/command to the bcm, but key in switch is there too. so looks to me like key in but off position it sends 12v to the pink/black. once moved to run it connects the 5v white wire to the pinkblack and then when moved to start it connects the 5v thru a resistor to the pink/black. dropping 5v to 3v maybe?

I'm mildly confused by why it's doing that or if I'm seeing something incorrect. but either way, I say all that but check for 12v at fuse 35 under the hood while in start and see what happens. if you keep 12v move to pin 4 of the ign switch and look for 12v while trying to start there.

the rest of the linked internal switches. acc and run it sends 12v to theft; yellow pin 2, transferr case; blue pin 10, tranny; blue pin 9, and ecm; blue pin 18 of connector X1


in run and start it sends 12v on pink to bcm so the bcm knows to turn on the run/crank relay under hood.

Thank you very much, i'll check these out tomorrow. It's almost like when radio HVAC lights all cut out when in crank position.

 

[Rockman101]

Thank you very much, i'll check these out tomorrow. It's almost like when radio HVAC lights all cut out when in crank position.

That's a good diagram but can't figure out where it hooks to on the fuse block. The red and white wire. Others are labeled. But that one isn't for some reason

 

[j91z28d1]

according to this, fuse 35 is right under the stater relay in the middle?

 

[Rockman101]

Well figure that out wire wasn't seated completely, but didn't fix the issue. Only other thing I can do is find a wire diagram for all the grounds make sure they are clean and good.

 

[Doubeleive]

Well figure that out wire wasn't seated completely, but didn't fix the issue. Only other thing I can do is find a wire diagram for all the grounds make sure they are clean and good.

my 2012 has a ghost in it.
occasionally if I disconnect the battery for whatever reason to do repairs, etc
upon reconnect I get a no start/no crank situation, it has done this since forever. while troubleshooting I determined that since I had not done anything that would affect the starting I tried disconnecting the battery again and then reconnecting and magically it starts and runs as if nothing ever happened.
digging a little more I found that when this happens it triggers a security fault, but no light on the cluster, clearing the fault with the scanner has the same affect as disconnecting the battery and it then starts and runs fine.
so... I tried replacing the security module, the ring around the ignition. bought new oem, connected to sps programmed it, sps indicates all is well, programmed known working key-no go, no security light, no start, nada...... multiple tries same results. I'm hours into it at this point....
I say f-k it, install old security module, (no reprogramming at all) insert key starts and runs!
so the problem remains, only sometimes if the battery is disconnected.
appears to be some sort of module handshake issue but it only happens with complete loss of battery power, 7 years no change it is the one and only thing this vehicle has ever done.

so anyway, curious if you are able to shift the transmission if you put your foot on the brake pedal and key is in run position?
also you may want to pull the underhood fuse box out, inspect it and the pins for any corrosion and re-seat the box.
the one and only other time I had a no start situation is when I had take it to a body shop for a fender bender repair and they had unbolted and moved the drivers fender and in the process the fuse box got bumped. they called me and said it wouldn't start so I went down to the shop and after a little messing around with it found the fuse box had been moved, re-seated the fuse box and walla! it started and worked fine.
the fuse box has been the culprit more than a few times in these kinds of situations, just food for thought.