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I am stuck..need help. Power to 8 coil packs but no spark from spark plugs.

Liz Kozel-Gill

By Liz Kozel-Gill
in Ask A GM Technician

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Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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I have a 2000 Chevy Silverado 1500 4x4 5.3LT,  I swapped out my 4l60e tranny for a used good running one, I struggled but got er in. I started her up and she was a little rough at first but ran fine, I put 4qts of ATF in and she read over full hot and cold check. So I pulled tranny to seat my torque converter, I didn’t pre fill it either. Anyway after that I couldn’t start her. So a new neutral safety switch I put in and new plugs to it. She would turn over but not start at this point. No spark it sounded like. So I checked the spark plugs and all 8 coil packs power to packs but not to plugs and no spark in any of them. So I proceeded to check all the fuses, relay’s & sensors that had anything to do with the ignition/ starter system. Everything was working. So I checked the PCM plugs, battery cables and all wiring to coil plugs. All the ground wires under the hood. I reset the security program in case it locked up something in the ignition system. I was told maybe check the Cam Shaft Position Sensor? I am at my wits end and still can’t get her to do anything but turn over, she started before?  What am I missing? All 8 coil packs are not getting power to plugs and all 8 plugs are not sparking it’s gotta be something simple? Please help no one on my end can figure it out.

Edited by Liz Kozel-Gill
Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

If it ran before the tranny swap, you need to go back and look over EVERYThING you touched. Something either got left unplugged, a bad wire broke inside the insulation making it very difficult to find, a wire is pinched in the bellhousing, or a ground or 2 was not reconnected.

Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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It started and ran after the swap, then I unbolted the bellhousing until I could put my little hands in there and seat the TQ, bolted it back up and put a new Nuetral Safty Switch and changed out both plugs. I checked everything I did twice to make sure I did it right and a buddy checked it as well, nothing would cause it to not spark from every spark plug? It’s something under the hood I think, just not sure what I have checked everything it seems like I am just spinning my wheels. Would the Crank Shaft position sensor cause no spark no start maybe….

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted (edited)

Yeah, crank position sensor will most definitely cause a no-spark condition. If when you're cranking you see zero tachometer needle movement, or the scan tool reads zero RPM, then more than likely the sensor is bad (Or the plug, or its wiring). You can test it with an incandescent test light while a helper cranks it over.

 

Could be something that got disturbed during the job, or could just be a coincidence that something failed in the ignition system.

 

I've had that coincidental failure happen to me. I changed a distributor assembly on a '96 Tahoe, and after installing the new one just happened to be the time the ICM failed. I chased my tail for DAYS on that one! Was a major contributor (Among a million other reasons) for me closing shop after 14 years. Stress city!!

 

This site is a pretty good help for diagnostic purposes: https://easyautodiagnostics.com/gm/4.8L-5.3L-6.0L/cmp-ckp-sensor-wiring-diagram-1

 

You can also search on that site for general ignition troubleshooting.

Edited by Jsdirt
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Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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Thank you I will check out that site and check out the crank position sensor..thank you so much I appriciate all your guys help so much!!!!

 

Thank you for the site it was perfect! I had the green wire totally disconnected from the Crank Pasition sensor plug! This certainly could’ve been the problem.I was wondering if you think that can be fixed or should I just get a new one? The way I had to shove the starter in and wiggle it out several times it’s so wonder that’s the only wiring problem there…lol Hopefully this will be the last part I have to buy this go around…Thank you sooo much again!!!

IMG_0633.jpeg

Edited by Liz Kozel-Gill
Wanted to add to my comment to Jsdirt.
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Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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Okay one of the wires on my Crankshaft Sensor has been pulled out can I fix it or should I just buy a new sensor?IMG_0633.thumb.jpeg.7315806e55111dad313da93fefd7c564.jpeg

IMG_0632.jpeg

Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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Okay if it’s the oil level sensor then this is what mine looks like can I just push it back into its hole or do I have to buy a new one?…IMG_0636.thumb.jpeg.6ec99fd83302130a0160b261a718847a.jpeg

Edited by Liz Kozel-Gill
CamGTP Senior Enthusiast

CamGTP

Posted
Posted (edited)

A new crankshaft sensor won't come with the pigtail. You will have to rewire/repin that pigtail to use it. Or you can try to source a new pigtail end. Those new pigtails usually come with 6in of wire and you just splice it into your existing harness.

 

The oil level sensor plug end, you can just try pushing the wires back into the plug to make it work. If the terminal ends don't lock into place, you'll need a new pigtail for that end too.

Edited by CamGTP
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Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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Thank you so much I appreciate all of your guy’s help. I couldn’t have found the problem without you all! Joining this site was the smartest decision I have made in a very long time!!! Thank you …Thank you …Thank you! I think you all saved my sanity!!🤪

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Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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Okay I changed the crank position sensor plug same thing crank but no start….& no spark still…Aaaarrrrrrggggggg!!!!!! What could it possibly be? No more wires are pinched or broken. I put a new Nuetral Safety switch in but I had the metal pin on it to make sure I had it adjusted right, I know that being off alittle will make it not start but will it also make the plugs have no spark? Any ideas anyone?

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Neutral safety switch has nothing to do with ignition - it will make it not CRANK, but won't cause a no-start due to no spark.

 

First thing I would do on this vehicle is find the plug on the driver's side valve cover that has an ignition ground passing through it, and connect a jump wire to it and connect the other end to a known good grounding point, be it the battery ground, or the stud on the firewall. If it fires up, you've found a bad ground. Very common issue on these trucks.

 

Next thing I would do if the above does nothing,  is double check that the wires are in the correct spots in the crank sensor's connector. And, test each one for the appropriate voltage or ground, and continuity to the engine computer. 

 

Just go to that link I posted prior and start testing things in the ignition system as it outlines. It should tell you what wires are what, what colors they are, and what you should see on them (And which order they should be in, in the connector).

 

To test the wiring itself, I unplug it from both ends, then try to power a halogen headlight through that particular wire. If it can light a headlight, the wiring is perfect.

 

Pay attention to all connectors (For corrosion inside, or poor contact due to spread or pushed in terminals), and any related wiring that's run through areas of heat and vibration (Focus on the sections that can move around a lot).

 

 

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Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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Don’t all plugs have a ground going through it? The ignition ground is a special ground wire? I took a picture of a plug that’s in the middle of the coil packs what is this plug? Is it the plug I am looking for?

IMG_0672.jpeg

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted (edited)

Yep, the spark plugs ground through the head right where they're screwed in. I can't recall if this wire you need to ground is for the engine computer, or all 8 coils, but it is definitely in the plug on the driver's side valve cover. Typically the computer controls the coil ground at the right time for spark, so it's probably not that. Been a few years since I've dealt with this.

 

That looks like the plug in the pic, but I'm not 100% sure since it's zoomed in close. If I remember right, the back right side is where the ground wire is (Naturally it's the hardest one to reach in typical GM fashion) ... BUT CHECK FIRST before connecting ANY to ground. 

 

I would get yourself a subscription to Alldata DIY - it will save you TONS of frustration. You don't want to ground the wrong wire and blow a fuse, spike the computer, or start a fire. Will be the best $20 you ever spent.

 

A safe way of checking for ground it with a test light hooked to battery positive - if you get the light to light using the sharp end, then you've found a ground. BUT, you can be lead astray by this at times by a dim light. Best to have a diagram so you know EXACTLY which wire is ground.

 

The diagrams combined with that troubleshooting link I posted a few days back will get you squared away.

 

EDIT: If I'm remembering things right, the ground source for that wire I'm talking about is located behind the power steering pump, bolted to the block.  The wire typically rubs and frays, or corrodes, and becomes disconnected electrically. It was always easier for me to just cut the wire near the plug and splice in a ground to the firewall.

 

https://www.alldata.com/diy-us/en/diy-repair-information

Edited by Jsdirt
Additional info I just remembered ... AND EDIT #2: forgot to post link
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