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2004 Chevrolet Trailblazer EXT LT I6 4L60e
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Discussion Starter · #1 · (Edited)
So I recently woke up one morning to a knock on my door from a family member asking for a jump because their battery just died.
So I get up, throw on some shoes and head out to my 04 TrailBlazer LT and start her up (nice) I walk over to put the cables on the dead battery and right as I turn around to do the same to my battery my TrailBlazer just shuts off as if I turned the key to turn it off.
At this point I’m like “okay that’s fine I’ll just try to start her back up” goes over turn the key and nope all she does is crank and I can begin to smell the gas so I stop and go check the fuse box and voila fuse #28 15amp is blown.
I put another 15amp fuse in and try to crank her up again and mid start the fuse blows and she goes back to resting.

What I’ve tried
1 unplug all the coils and try to start and see if that blows the fuse and surprisingly no, okay so I go and check all my coils and they seem to check out.

I unplugged the fuel harness that leads to the fuel injectors and tried to start it and surprisingly the fuse didn’t blow. (Mind you the coils are plugged back in)

I removed the belt thinking that it could possibly be my alternator and what do you know she started right up and ran until I got uncomfortable at the fact that she might over heat.


Can I get some assistance on this? Please.
 

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2004 gmc envoy_slt
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The alternator has no direct relation to this voltage. I suspect you may have a wiring issue such a wire being abraded and shorting to a metal somewhere. And this seems to be related to the Pink wires going to the ignition. Take a careful look at these wires in the harness.
 

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2004 Chevrolet Trailblazer EXT LT I6 4L60e
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Discussion Starter · #3 ·
The alternator has no direct relation to this voltage. I suspect you may have a wiring issue such a wire being abraded and shorting to a metal somewhere. And this seems to be related to the Pink wires going to the ignition. Take a careful look at these wires in the harness.
okay noted! I’m going to try and takeout as much of the harness as possible and check for continuity within each wire while checking for any wires being abraded.
 

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2002 chevy trailblazer_lt
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Another approach is to pull the fuse and hook up a test meter set to continuity from the load side of the fuse to ground. Having a beeping meter helps here. Then move along the harness wiggling the bejesus out of things. If the meter beeps or the reading changes dramatically you may have found the issue.
 

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2004 Chevrolet Trailblazer EXT LT I6 4L60e
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Discussion Starter · #5 ·
The alternator has no direct relation to this voltage. I suspect you may have a wiring issue such a wire being abraded and shorting to a metal somewhere. And this seems to be related to the Pink wires going to the ignition. Take a careful look at these wires in the harness.
Okay. I know how you said the alternator has no relation to the PCM 1 fuse but when I disconnected the alternator wire from the battery she started right up without issues and is running just fine on the battery. (Now check this out) When I go to connect the alternator wire back to the battery the fuse blows almost instantly.
Think maybe a bad alternator?
 

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2004 Chevrolet Trailblazer EXT LT I6 4L60e
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Discussion Starter · #6 ·
Another approach is to pull the fuse and hook up a test meter set to continuity from the load side of the fuse to ground. Having a beeping meter helps here. Then move along the harness wiggling the bejesus out of things. If the meter beeps or the reading changes dramatically you may have found the issue.
Yes. I tried that and my voltmeter just shows a lot of “Steady” resistance.
 

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Okay. I know how you said the alternator has no relation to the PCM 1 fuse but when I disconnected the alternator wire from the battery she started right up without issues and is running just fine on the battery. (Now check this out) When I go to connect the alternator wire back to the battery the fuse blows almost instantly.
Think maybe a bad alternator?
To me this suggests you may have wiring in that harness that has overheated and fused itself to an adjacent, unrelated wire. I saw a post last year someplace where a fellow was tracing out an alternator issue and when he opened up that harness found melted wiring. You may have such an issue here.
 

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2004 Chevrolet Trailblazer EXT LT I6 4L60e
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Discussion Starter · #8 ·
I appreciate you guys help. I eventually figured out the problem, it was that new driveworks coil I installed all along 🤦🏾‍♂️ Can’t believe I second guessed it. I took it back and got a refund and Instead opt for a duralast coil from autozone and she runs flawlessly.
 
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