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No signal to one coil

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Old Sep 12, 2023 | 11:37 PM
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Originally Posted by Drakecloude96
What about a bent reluctor wheel? Would it throw a code other than the code for the coil thats not firing?
There is no reluctor, no distributor, on a V-10. Crank signal triggers directly from the machined crank counterweight. The coil fires two cylinders at once, one on exhaust, like an old Harley. The power to the coil should be always hot, provided by the ASD relay, the green/orange wire? PCM provides the ground. If that is so, and you can check it, then you may have an open power, open ground. The wiring on these trucks is fragile due to heat. May not be enough to check for continuity, but for voltage passed, or voltage drop, if that makes sense.
 

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Old Sep 13, 2023 | 07:52 AM
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Originally Posted by 69_XS29L
There is no reluctor, no distributor, on a V-10. Crank signal triggers directly from the machined crank counterweight. The coil fires two cylinders at once, one on exhaust, like an old Harley. The power to the coil should be always hot, provided by the ASD relay, the green/orange wire? PCM provides the ground. If that is so, and you can check it, then you may have an open power, open ground. The wiring on these trucks is fragile due to heat. May not be enough to check for continuity, but for voltage passed, or voltage drop, if that makes sense.
I think the coils will only have power for a few seconds, unless the PCM sees the engine turning....
 
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Old Sep 13, 2023 | 02:09 PM
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Fair enough. "The power to the coil should be always hot..." While running. His engine runs, therefore..... Back to wiring.
The function of the cam sensor is to tell the PCM where the crank is in it's 720deg of rotation, and provide evidence of life. No cam sensor, no life, no ASD power. Replacing the crank sensor on an engine that runs sounds like forum parrots talking.
This is my OBDII bible. Have one for '95 as well. Try to get away from the idea that you need the DRB scanner. Voltmeter, continuity light, jumper wire and a wiring diagram will let you do much of what is in here following the logical steps. Forum parrots tells you to throw unnecessary parts at a truck without figuring out what is wrong.


Looks like Hey You is right to me.
 

Last edited by 69_XS29L; Sep 13, 2023 at 02:11 PM.
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Old Sep 13, 2023 | 02:13 PM
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Here is one way to think about the problem.
 
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Old Sep 13, 2023 | 02:45 PM
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Thats some good things to check. I do get a code for the secondary coil. I'm assuming it's the same test procedures as the primary coil that you posted those pictures of? With the exception that it's a 4 coil pack not a 6 on the secondary.
 
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Old Sep 14, 2023 | 12:07 AM
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What codes are you getting? I can screenshot the diagnostic tree for that code if you like.
You also need a service manual/wiring diagram to track stuff like this down. Hey You can provide a link for downloadable manual, pretty sure.
 
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Old Sep 14, 2023 | 06:30 AM
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The one that runs 4 is only firing 2 of them. I have replced the coil again thinking maybe I fried it with a bad ECM but still the same problem. I seem to not be getting power to the signal wire for that coil.
The pcm will fire the coil with a ground pulse and the asd relay supplies the 12V. If you are not getting the ground pulse i would confirm that you have good continuity from the coil wires to the pcm. If that is good it has to be the pcm not firing those wires or by some chance that the crank sensor is not sending a signal at those cylinder locations. Most scanners won't give you a graft of the can/crank signals(like in my previous post) that the pcm sees only the higher end ones.
 
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Old Sep 14, 2023 | 07:59 AM
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Originally Posted by Moparite
The pcm will fire the coil with a ground pulse and the asd relay supplies the 12V. If you are not getting the ground pulse i would confirm that you have good continuity from the coil wires to the pcm. If that is good it has to be the pcm not firing those wires or by some chance that the crank sensor is not sending a signal at those cylinder locations. Most scanners won't give you a graft of the can/crank signals(like in my previous post) that the pcm sees only the higher end ones.
The pcm isn't sending the pulse signal from what i can tell with a multimeter. Also i checked continuity and it is reading the same as all the other pulse wires. I cleaned the connection on the new crank sensor that was corroded and cleaned the connection at the pcm as well. Still no change.
 
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Old Sep 14, 2023 | 08:01 AM
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If you aren't getting power to the coil, the PCM isn't going to be able to fire those cylinders......
 
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Old Sep 14, 2023 | 08:09 AM
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Originally Posted by 69_XS29L
What codes are you getting? I can screenshot the diagnostic tree for that code if you like.
You also need a service manual/wiring diagram to track stuff like this down. Hey You can provide a link for downloadable manual, pretty sure.
I am getting a p0353 code. I am also getting a generator field code that I don't recall the number on right now.
 
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