06 suburban 1500 not starting

Feel-The-Pern

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If I jump the relay, it starts just fine until it sits for 8+ hrs. I replaced the relay. Still same issue. Replaced the ignition switch and no luck there either. Any suggestions on where to go from here would be greatly appreciated.

Thanks
 

zora

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Are you saying if you jump the relay first thing in the morning, the rest of the day it starts without having to jump it until the next day?
 

Feel-The-Pern

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Are you saying if you jump the relay first thing in the morning, the rest of the day it starts without having to jump it until the next day?
Yes, give or take the amount of driving I do that day. If I'm running errands, it will start all day after the first jump.
 

zora

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The relay you are jumping is in the underhood fuse box, square shaped and there is an identical square shaped relay next to it?
I know you replaced it but have you tried swapping the new one with the relay next to it?
 

Feel-The-Pern

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The relay you are jumping is in the underhood fuse box, square shaped and there is an identical square shaped relay next to it?
I know you replaced it but have you tried swapping the new one with the relay next to it?
No I have not. I do have the old relay still. I will try that and let you know. Thanks
 

zora

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You have a wiring diagram that showed you what pins to jump on the relay?
 

Feel-The-Pern

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You have a wiring diagram that showed you what pins to jump on the relay?
There is a diagram in the box under the hood. The way I figured it out was YouTube. Watched a bunch of videos and finally found one doing what my rig is doing, unfortunately it only shows how to start it and never came back with a comment on what was causing it.
 

zora

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There is part of the starter circuit in the link below.
I assume when it wont start, moving the shifter into neutral has no effect?
The security light is off?
 

Feel-The-Pern

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Haven't had luck with the neutral part.

Are you referring to the security light or the passkey light? I have both. Passkey light is on because I replaced the ignition switch. Definitely going to look into the pcm though. Have had a recent O2 sensor reading & lack of get up.
 

zora

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You didnt do a relearn procedure for the ignition switch?
 

zora

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2006 uses Passlock, not a chipped key. There is a magnet on the lock cylinder which when turned generates a signal. It cuts off fuel.
Not sure how you wouldn't have starting problems if you didnt program the new cylinder.
 

Feel-The-Pern

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Well that's good to know, but still doesn't make sense. How in the world is it able to start if it's supposed to have the fuel pump shut off?? This is definitely confusing. If the ECM isn't working properly, would it interfere with the passkey feature? If the car starts, can I attempt the passkey reset or only when it doesn't start?
 

zora

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If you have the security light on, the lock cylinder you installed isnt recognized.
Did it come with programming instructions?
 

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Did you have a security light on before you changed the switch?
You mention a security light and a pass key light, I find no mention of the second light in the owners manual.
 

zora

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In post #10 above you state the Passkey light is on, what are you referring to?
 
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