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Discussion Starter #1
So I get this code sometimes and sometimes I don’t. Most of the time it’s when the truck has been sitting for a little while (few hours) And after it kills the engine and turn the light on it will crank right up and run fine and great even if I need to turn the truck off and crank it back it. It’ll be as easy as bump the starter almost (May be exaggerating a bit , but still). But if I let it sit a little bit it’ll kick the code again and kill the motor then be fine once again. Every sensor on the engine has been changed along with all the ignition parts as well. I changed the ICM connector also. And I added a another engine ground just in case. What do you guys think?
 

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I don’t know what you are trying to show me? I already know what the codes means hence the pictures. So I’m not sure why you posted what you posted. All it took me to was to show me what the code meant but obviously I already know that.
Did you check all the things others suggested to check at Poncho's link? Like proper fuel pressure, etc...
 

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Discussion Starter #5
I don’t know what you are trying to show me? I already know what the codes means hence the pictures. So I’m not sure why you posted what you posted. All it took me to was to show me what the code meant but obviously I already know that.
Did you check all the things others suggested to check at Poncho's link? Like proper fuel pressure, etc...
When I clicked the link it didn’t take me to anything like that. But I have checked a lot of other stuff which is why I am here. I was
Hoping someone had other ideas.
 

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What does the code mean then?
please explain
 

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The description of the code on your scanner is pretty poor.
Thats OK.
Gimmee a minute and I will try to elaborate
 

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If you understand how the setup works it makes sense.
1 the engine crankshaft sensor generates a pulse
2 that pulse is used by the Computer ( PCM/VCM)
3 It (The PCM) processes the signal and hands off a signal to the ICM (Ignition Control Module)

4 the module turns the coil on and off by using the signal, in turn it fires the coils
5 The code is generated when :
A - the engine computer (PCM/VCM) is seeing a rpm signal of less than 250 rpm while the PCM has the ICM module circuit actively processing the ignition signal ( electronic spark timing is running in PCM)

What this boils down to, is that the code is pretty generic and is intended to direct you to check the ICM and EST function of the ignition circuit.

Ya following me so far?
 

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Discussion Starter #16
If you understand how the setup works it makes sense.
1 the engine crankshaft sensor generates a pulse
2 that pulse is used by the Computer ( PCM/VCM)
3 It (The PCM) processes the signal and hands off a signal to the ICM (Ignition Control Module)

4 the module turns the coil on and off by using the signal, in turn it fires the coils
5 The code is generated when :
A - the engine computer (PCM/VCM) is seeing a rpm signal of less than 250 rpm while the PCM has the ICM module circuit actively processing the ignition signal ( electronic spark timing is running in PCM)

What this boils down to, is that the code is pretty generic and is intended to direct you to check the ICM and EST function of the ignition circuit.

Ya following me so far?

Yeah. I’ve replaced all my sensors and ignition components. Should I replace the computer now?
 

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The crux of the whole code is that , the PCM is processing ignition signal and timing ( very important) and sending the signal to the ICM.
But the RPM is too low ( less than 250 rpm) which indicates an engine that hasnt started ,or started as expected.

So the PCM processor is running the algorythms that calculate all these functions , see.
Therefore , the PCM sees active RPM signal, and it also senses that it (internally) is calculating ignition timing, and sending a trigger signal to the ICM, but the engine rpms is to low. So it thinks the engine is not starting, or slow to start, and the computer algorythms generate the code to indicate the igntion circuit is high, as it calculated that it is not firing . It is meant to lead you to checking connections and secondary ignition components.

Since it is an intermittent code, I would hazzard a guess at connectors/connections.
One other item could be the PCM is not generating a signal fast enough to fire the ICM/Coil because of an internal failure. Your gonna need some skills on a Oscilliscope for that one.

Havin any fun yet?
 

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Yeah. I’ve replaced all my sensors and ignition components. Should I replace the computer now?
Not yet, you got some checking to do, unless you have a KNOWN good PCM laying around, because if the PCM doesn fix it then you still have a wiring/connection problem

My bet is on connections
 

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Discussion Starter #19
The crux of the whole code is that , the PCM is processing ignition signal and timing ( very important) and sending the signal to the ICM.
But the RPM is too low ( less than 250 rpm) which indicates an engine that hasnt started ,or started as expected.

So the PCM processor is running the algorythms that calculate all these functions , see.
Therefore , the PCM sees active RPM signal, and it also senses that it (internally) is calculating ignition timing, and sending a trigger signal to the ICM, but the engine rpms is to low. So it thinks the engine is not starting, or slow to start, and the computer algorythms generate the code to indicate the igntion circuit is high, as it calculated that it is not firing . It is meant to lead you to checking connections and secondary ignition components.

Since it is an intermittent code, I would hazzard a guess at connectors/connections.
One other item could be the PCM is not generating a signal fast enough to fire the ICM/Coil because of an internal failure. Your gonna need some skills on a Oscilliscope for that one.

Havin any fun yet?
Yeah. I’ve replaced all my sensors and ignition components. Should I replace the computer now?
Not yet, you got some checking to do, unless you have a KNOWN good PCM laying around.

My bet is on connections

Okay I’m going to check and replace more connectors. They are 20+ years old so it would hurt and it’s very inexpensive.

That’s a hell of a theory of operation you just gave me. It’s was pretty great and I am deff going to save it. Where do
You find stuff like that for vehicles or did you generate that yourself just now?
 

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I wrote it up .

I understand how these things work (somewhat) and the condition for setting the code was less that 250 RPMs with Electronic spark timing enabled.

That was the 2 parameters involved for the algorythm to generate the code. So

Its still kinda generic.
 
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