2007 Denali wont start after cylinder head replacement

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CAPT75

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Hello all,
I'm incredibly stumped. After almost 4 months (due to lack of free time) of my truck sitting in the garage, i finally got it all together and the damn thing won't start. I discovered that cylinder 5 had zero compression. I pull the head and one of the valve seats is about 1/4" out of place. Take it to a machine shop to get it all fixed and cleaned up and put it back in. During the compression test I had thought my starter was bad so I put in a new one, turns out my old one was fine so after it sat on my garage floor for a month, I put the old one back in and returned the new one. I replaced the starter through the wheel well so maybe I damaged the ABS stuff while I was in there? That's the only time I touched the starter or wiring going to it. When I pulled the head I had to unplug the wiring to the upper intake manifold, coils, injectors, alternator etc. There was a braided metal strap attached to the head, assuming that was a ground? That's reattached. Didn't remove anything that wasn't absolutely necessary. So now everything is back together and I charged the battery (it was completely dead) I go to start it and I get absolutely nothing from the starter at all when I turn the key. No crank, no click, no sound, no nothing. On the dash there are three lights staying on, ABS, check engine, and the triangle with the car in it and wavy lines, assuming traction control? On the info screen its saying "Stabilitrak off, traction control off, park assist off, service suspension system". I can shift gears when the key is ON and I press the brake but there is no indicator line under the gears in the gauge cluster screen to tell me what gear I'm in. I'm getting power to accessories, but the door locks don't work, the dome lights don't come on, and the power running boards don't come down when I open the door. Scanned with an OBDII and I get no codes. What the heck is going on with this thing?!
 

Big Mama

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What happens if you jump start it? The lights on the dash do sound like a wheel speed sensor may be unplugged. Usually the abs light sets off the traction control light too. Check your ground again and if all looks well eliminate the battery with a jump start or different one
 
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CAPT75

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The battery has been hooked up to a charger/jump box for two days, so it should have plenty of power. Could the inability to start have something to do with the security system? The security light comes on the dash when I first turn the key but turns off after about 5 sec. I’m out of town so I’ll check the grounds and speed sensor when I’m back home and report back. Could the ABS light issue also be causing the “service suspension” message on the gauge cluster screen? I also read somewhere that to feel the starter relay in the fuse box while someone turns the key to see if it clicks and that’ll tell you if it’s getting the ignition signal.
 

petethepug

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Look for the ez stuff first. Plug /coil wires are placed correctly and 200% sure? Plug wires damaged or lost continuity during removal?

The dash indicator lights will do what your describing if one of the plug wires is left off. Obviously thats not the case so it leads to a concealed open in a coil or coil harness.


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Big Mama

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But even with all that it should still turn over right? Yes the abs and suspension light and traction control lights can be related. Anxious to see what a good battery does. Check what it’s got before installing it. I just charged my bike battery overnight and it showed 13.8v not sure if a truck battery would be higher
 
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CAPT75

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Looks like it'll be on hold for a moment since over the weekend I rolled my ankle, strained my calf and hyperextended my leg :favorites68: I did check the starter relay in the fuse box and it's clicking when turning the key, so that should mean the relay and ignition switch are good, which only leaves the starter itself, right?
 

Big Mama

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Good grief man. You’re having a tough go. You can always rap the starter with a hammer a few times to see if turns over. If so, no question
 
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CAPT75

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So my leg is finally healing to the point where I can get around decently enough, so I’m going to pull the starter tomorrow and get it tested to eliminate that. Does anyone know where I can get a schematic of the starting circuit? I was reading that the starting circuit may or may not pass through the BCM and/or PCM. If it is, and the starter is also fine, what could be causing the BCM/PCM to block the signal to the starter? The only wiring I removed and replaced during the cylinder head replacement were the spark plug wires and the upper harness to the upper intake manifold, coils, injectors, alternator, etc.
 

wjburken

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When I replaced the Cam on my ‘07 XL Denali and got everything back together, I experienced the same thing. It ended up being the starter.

Can you check to see if you have voltage at the starter when you turn the key?
 

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