Electrical

[BegottenOne]

I have replaced the starter, alternator, battery, belt, and ignition switch on my 04 yukon. It still hesitates to start what else can it be. All cables and grounds are tight. The starter will engage but won't turn the engine over.

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[iamdub]

Poor ground connection from the battery to the frame and/or engine to frame? Damaged (corroded) cable from the positive battery post to the starter solenoid?

I know you said they are tight. But did you actually remove them and inspect for corrosion between the contacting surfaces and inside the jacket behind the crimped connectors?

 

[Tonyrodz]

How's your fuel pressure? Could also be a bad fuel pump. Try banging on the gas tank as someone turns the key.

 

[BegottenOne]

Fuel pressure is good. All cables are tight and connections are clean no rust or dirt on them

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[iamdub]

Wait- by "won't turn the engine over", you mean the solenoid on the starter engages but the starter won't spin the motor or the motor spins as it should when starting but doesn't fire up?

 

[BegottenOne]

Wait- by "won't turn the engine over", you mean the solenoid on the starter engages but the starter won't spin the motor or the motor spins as it should when starting but doesn't fire up?

It acts like the battery is dead but if I leave the key in the "on" position for 15 to 20 secs it drags like a low battery but engine turns over

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[Chubbs]

a tight connection won't matter if corrosion has built up in The wires beneath the clamps. You have to remove each clamp and scrub everywhere with a wire brush before securing well with the bolt, which should also be cleaned well.

We aren't talking about the obvious attachment posts, but the wire underneath the clamps, that you can't see without disassembling.
I actually had some $hit identical to this short of the positive lead terminal that connects to the battery. AFTER I loosened the post clamp from the wire/lead, I found this corrosion underneath that could not be seen otherwise. Scrubbed it all out, secured it back to the clamp, reconnect to Pos terminal, good as new. I think you are overlooking something.


Look here


Remove these

 

[BegottenOne]

a tight connection won't matter if corrosion has built up in The wires beneath the clamps. You have to remove each clamp and scrub everywhere with a wire brush before securing well with the bolt, which should also be cleaned well.

We aren't talking about the obvious attachment posts, but the wire underneath the clamps, that you can't see without disassembling.
I actually had some $hit identical to this short of the positive lead terminal that connects to the battery. AFTER I loosened the post clamp from the wire/lead, I found this corrosion underneath that could not be seen otherwise. Scrubbed it all out, secured it back to the clamp, reconnect to Pos terminal, good as new. I think you are overlooking something.
View attachment 181959

Look here
View attachment 181960

Remove these

View attachment 181961

I replaced both positive and negative terminals ends on battery cables when I replaced the battery. New nuts and washers and connectors on starter well. It's has to be something so simple that I'm over looking it but I'm dumbfounded on what it could be.

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[Chubbs]

I replaced both positive and negative terminals ends on battery cables when I replaced the battery. New nuts and washers and connectors on starter well. It's has to be something so simple that I'm over looking it but I'm dumbfounded on what it could be.

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I hate that you are getting so much aggravation from this. and you don't have a CEL or any fault codes, correct? its common to experience CEL fault codes and/or error messages (DIC) for the transmission and ABS as those extensions flip out when hit with anything lower than your normal or spec voltage output.

Without knowing the history and jumping to conclusions, I would next be replacing the main leads & upgrading the gauge; its a mod called "the big 3," I believe, if for anything but an upgrade & possibly eliminate the culprit in process.
I would also be stopping into Oreilly Auto and getting whatever tested that I can. Maybe 1 of the new parts is compromised.

 

[Chubbs]

And before attaching the new clamps onto the cables you didn't do any prep work? That's where my issue was but I had to actually spread the wires out and scrub all of the corrosion out; it was embedded within the individual strands, I didn't see much outward sign of corrosion or contamination such as your typical green&ashy on the batt post & cable clamp as I clean that reg. I had to disassemble everything then untwist & spread the individual strands to find the root cause.