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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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Duelin Enthusiast

Duelin

Posted
Posted

I have gone back and read your post. I didn't see where that you have verified that you have an RPM reference from the crank sensor while cranking. Do you? If so disregard.

  • 3 weeks later...
Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

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On 1/11/2024 at 10:23 PM, Jsdirt said:

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

Hey bud well I ended up buying a new Crankshaft Position Sensor and put it in. I ran a diagnostic tester on my truck before trying to start it, it said Left front wheel speed sensor circuit open…? Now I don’t know what that means but it sounds like something I should fix before starting it…right? Can I close the circuit? Wow anything else want to  come up so my truck stays broke down for another 8 months?

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

That has nothing to do with the no-spark condition. I'd concentrate on the no-spark issue, and worry about ABS issues later.

 

That's all that wheel speed sensor does - sends a wheel speed signal to the ABS module, which compares the speed to the other 3 wheels, and activates the ABS if one wheel slows from the others or stops moving altogether (When sliding on ice or dirt for example). 

 

ABS won't matter if you can't get the vehicle to move. 😊

Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

Posted
  • Author
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On 1/4/2024 at 9:32 PM, Jsdirt said:

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.

   Okay so I changed the Crankshaft Position Sensor plug….no change. So I bought and replaced the sensor as well…no change.  Could the oil level sensor plug cause the no start? I ran a diagnostic reader and got 41 C- codes and 14 P-codes. Now after I freaked out I realized a lot of the codes with inactivity and performance in them were only coming up because she has not moved or drove anywhere since the tranny swap like 8 months now, so I am trying to eliminate the codes down to maybe what my problem is. What a way to make yourself crazy!! My truck had no codes prior to all this so the PCM or the brain of course would not have any memory because I cleared it disconnecting the battery. I have pulled the PCM to check for corrosion they were clean as a whistle. So I am still at square one no spark out of any of the 8 coil plugs!! I have to get my truck running again work will be starting up again and I have put a butt load of money into this and I am broke, frustrated and at my wits end….where do I go from here???? Please help. Thank you all for all your help and knowledge, I so appreciate you all!!!
      Should I test the COP coils? Idk……

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted
2 hours ago, Liz Kozel-Gill said:

41 C- codes and 14 P-codes. Now after I freaked out I realized a lot of the codes with inactivity and performance in them were only coming up because she has not moved or drove anywhere since the tranny swap like 8 months now

You might be able to eliminate some, a truck not moving wouldn't necessarily generate a code. Clear all the codes (sounds like you have a reader) then scan again, post them all here.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted (edited)
9 hours ago, Liz Kozel-Gill said:

   Okay so I changed the Crankshaft Position Sensor plug….no change. So I bought and replaced the sensor as well…no change.  Could the oil level sensor plug cause the no start? I ran a diagnostic reader and got 41 C- codes and 14 P-codes. Now after I freaked out I realized a lot of the codes with inactivity and performance in them were only coming up because she has not moved or drove anywhere since the tranny swap like 8 months now, so I am trying to eliminate the codes down to maybe what my problem is. What a way to make yourself crazy!! My truck had no codes prior to all this so the PCM or the brain of course would not have any memory because I cleared it disconnecting the battery. I have pulled the PCM to check for corrosion they were clean as a whistle. So I am still at square one no spark out of any of the 8 coil plugs!! I have to get my truck running again work will be starting up again and I have put a butt load of money into this and I am broke, frustrated and at my wits end….where do I go from here???? Please help. Thank you all for all your help and knowledge, I so appreciate you all!!!
      Should I test the COP coils? Idk……

Check to see if the 5V reference is still there. If that's shorted, or pulled to ground by ANY sensor that uses it, it'll throw codes galore and never start.

Edited by Jsdirt
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  • 3 weeks later...
Liz Kozel-Gill Enthusiast

Liz Kozel-Gill

Posted
  • Author
Posted (edited)

I have pulled the starter again and realized I pulled the power wire apart for the Crankshaft position plug! Put it back together with a better connection and put the starter back in carefully this time so I don’t pull apart anymore plugs!!! She started right up!!! Yeah!! But now I have put 5 of 11 quarts of ATF in and didn’t pre fill my Torque Converter it’s reading way over full and won’t go into gear. I was told to let it idle for awhile so the fluid could warm up & have time to fill the TQ.it is still idling and hasn’t gone down yet on the dipstick. What could it possibly be? The TQ is seated properly and it’s rare the pump goes, so what should I do? Help!!
 

Edited by Liz Kozel-Gill
Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Nice - glad it started! One hurtle cleared. :thumbs:

 

Overfull can be just as bad as low. If you're seeing bubbles on the dipstick, you'll need to draw out any extra ATF from the transmission. Foam won't move the vehicle. 

 

But if it's not foamy, your transmission could be smoked. Usually when you start the engine, the converter fills in SECONDS. No need to warm it up, or "wait for it to fill". I would try shifting through ALL the gears, counting to 5 in each gear before shifting to the next. That'll purge out any air in the valve body. 

 

Was the transmission recently serviced? I can't recall what was mentioned in the first post & I'm short on time to go back & read. If it wasn't serviced, there shouldn't be any air anywhere in the trans..

 

 

Hot Blonde New Member

Hot Blonde

Posted
Posted

Well i have got 6 qrts of ATF in it now so its still takung fluid maybe just the dipstick is not reading right that is where i put the fluid in anyway. ... maybe when i get up to 9-10 qrts it might start shifting into gear? Yes I am so excited about it starting! If i can just get the 11 qrts in and it goes into gear and moves i would be finally back pn the road! I guess we just cross our fingers for now....??

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

If the trans was completely rebuilt with a new converter, 10-11 quarts is about right. 

davester Senior Enthusiast

davester

Posted
Posted (edited)

Of course, way back, you mentioned:

-installing the transmission

-running the engine

-separating the transmission from the engine to re-seat the torque converter

 

If you ran the engine, with the TC not properly engaged with the trans oil pump, you may have damaged the oil pump.

I know with the 4l80e, it's a fast way to wipe out the pump, and it's probably similar w the 4l60e (if the engine is run, with the TC not properly engaged with the oil pump in the transmission).

Edited by davester

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