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Here is what to do man....

Put a voltmeter on the ICM and patch it with a pomona or other acceptable backprobe .
Hook the backkprobe to Ignition control module Pin letter "B". It will be a white wire.

That is the wire that signals the ICM to fire.
There will be a .5-4.5 volts AC signal on that wire.

The fact it starts and dies means that right after startup the signal is dissapearing , for one or another reason. Maybe a wire connector , maybe the PCM is failing to generate the signal.

Need to pin it down to that signal and that is going to be tough without a scope.
You will need to monitor rpm, and voltage on pin B and need to them to be graphed in sync. on a scope so you can compare them.
If the rpm at the crank sensor is present , and the EST pulse from the PCM drops out, and you have ruled out any connection problems, the only reasonable deduction is the PCM is failing
 

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You can monitor rpm with the scanner and read the voltage at pin B with a voltmeter set to AC volts.

It will be a race for your eyes to see if the RPMS drops according to the actual engine rpms percieved by senses and if the ICM trigger signal drops out first and is causing it.

That is why a scope is handy because it charts both these readings IN REAL TIME, so its like a chart or graph you can easily see who drops out first by scrolling through the stored values.
 

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Hates: Liver. Loves: Diesel
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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.
Take a look at the very first result in the search he linked. There are detailed instructions for chasing down the fault that causes that code.

By all means, there is no need to replace all the connectors. GM Weatherpack connectors last darn near forever. It's possible that something is corroded, but I don't see a need for replacement. That will just take days and there isn't anything to suggest that will fix everything. Find the fault and fix that one thing.

My initial guess is that some wire got melted, chewed, or worn through, but I'm not there so I can't venture a guess. Start digging using those instructions on the page he linked to. When you find it, it will likely be obvious.
 

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Discussion Starter #24
Here is what to do man....

Put a voltmeter on the ICM and patch it with a pomona or other acceptable backprobe .
Hook the backkprobe to Ignition control module Pin letter "B". It will be a white wire.

That is the wire that signals the ICM to fire.
There will be a .5-4.5 volts AC signal on that wire.

The fact it starts and dies means that right after startup the signal is dissapearing , for one or another reason. Maybe a wire connector , maybe the PCM is failing to generate the signal.

Need to pin it down to that signal and that is going to be tough without a scope.
You will need to monitor rpm, and voltage on pin B and need to them to be graphed in sync. on a scope so you can compare them.
If the rpm at the crank sensor is present , and the EST pulse from the PCM drops out, and you have ruled out any connection problems, the only reasonable deduction is the PCM is failing
You can monitor rpm with the scanner and read the voltage at pin B with a voltmeter set to AC volts.

It will be a race for your eyes to see if the RPMS drops according to the actual engine rpms percieved by senses and if the ICM trigger signal drops out first and is causing it.

That is why a scope is handy because it charts both these readings IN REAL TIME, so its like a chart or graph you can easily see who drops out first by scrolling through the stored values.
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.
Take a look at the very first result in the search he linked. There are detailed instructions for chasing down the fault that causes that code.

By all means, there is no need to replace all the connectors. GM Weatherpack connectors last darn near forever. It's possible that something is corroded, but I don't see a need for replacement. That will just take days and there isn't anything to suggest that will fix everything. Find the fault and fix that one thing.

My initial guess is that some wire got melted, chewed, or worn through, but I'm not there so I can't venture a guess. Start digging using those instructions on the page he linked to. When you find it, it will likely be obvious.
Crazy thing is, it doesn’t happen all the time and when it does happen it only happens on start up. while running, it runs beautiful. But it also doesn’t always happen when I crank the engine sometimes it cranks perfect and then sometimes it generates the code then immediately dies but then cranks perfect the next try. So it’s kind a hard to assume when it’s going to happen.
 

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Hotrodders.com Moderator
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Yep. Fuel pressure could also cause it to die and set the code.

Remember parameters 250 rpm and EST signal being generated.
If the fuel goes away the rpm drops below 250, EST signal present ... BOOM P1351
 

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Yep. Fuel pressure could also cause it to die and set the code.

Remember parameters 250 rpm and EST signal being generated.
If the fuel goes away the rpm drops below 250, EST signal present ... BOOM P1351
The messed up part is it has nothing to do with electrical connections. HA HA

The self diagnostic algorythms in the early OBD2 systems really stinks sometimes
 

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Discussion Starter #27
Yep. Fuel pressure could also cause it to die and set the code.

Remember parameters 250 rpm and EST signal being generated.
If the fuel goes away the rpm drops below 250, EST signal present ... BOOM P1351
Is there any significance to it saying on cylinder one, like what if I have a dirty injector at that spot and when it cranks off cylinder one it cranks slow and generates the code. So could a dirty injector cause It to crank slow then in turn generate the code?
 

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The cylinder 1 mention doesnt make sense to me.
 

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Time to bust out some tools and get to testing

Keep track of results . Write stuff down for reference.
 

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Hates: Liver. Loves: Diesel
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OBDII codes are not answers. The PCM is remarkably dumb. Let's say you get a code P0300 which is random misfire. It isn't telling you that the ignition system is messed up, it's saying that the CKPS is registering that there is a misfire based on uneven pulses reaching a threshold that is outside the acceptable range. OBD codes don't tell you what to replace, they tell you where to start looking. It's giving you clues so you can be Sherlock Holmes and figure it out. A P0300 code could be plugs, wires, coil, water somewhere it shouldn't be... but it could also be a vacuum leak, torn intake boot, failing injectors, fuel pump, fuel pressure regulator, fuel filter, or even (rarely) an O2 sensor, and I have actually seen it happen because of oil pressure not keeping the valve lifters pressurized and letting several cylinders randomly drop cylinder pressure. On the extreme side of things, I have seen a P0300 code for cracked piston rings causing intermittent loss of cylinder pressure and tripping that code. In the case of a P0300, I would attack it by reading real-time data on a scanner. If it shows that fuel enrichment is at +12% and O2 sensors are reading normally, I would first check fuel pressure and vacuum leaks before the TB. If the fuel trim read +20%, O2s reading -10%, and I also had a P0171, I would look for an exhaust leak between the engine and the upstream O2 sensor. That is how a misfire code would lead me to check fuel, vacuum, and exhaust instead of wasting time chasing ignition components. That's how you use the codes. That whole "this is what others reported fixed their problem" feature on your scanner should be 2000% ignored. I wish they never put it on there. You have to think like a PCM.

Reported fixes are like a 3-year old saying that they ran "way faster after buying new sneakers." 8 times out of 10, this is what happens with those reports: Person gets that code, reads first suggested fix, throws that part at the problem, clears the code, drives it for 20 minutes, code doesn't come back, reports the fix. Then the next morning they get the code again on the way to work, so they throw the second part at it, but don't report that the first fix didn't work. Ignore those suggested fixes.
 

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Post #30 is EXCELLENT

Early OBD2 Computers ARE DUMB. :thumbup: LOL

The reference to any cylinder doesnt make any sense to me at all with this code Curtis.
Its more related to engine speed and ignition signal

I have used a lot of different scanners and sometimes the verbage is pretty inaccurate, wierd, or just plain confusing
 

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Misfires can be detected 2 ways.

Secondary voltage spikes, or primary voltage levels as a result of said spike.

Or the PCM runs a counter/timer that parallels the engine speed and crankshaft rpm and tooth count.When the counter falls out of sync, it sets a misfire on whatever cylinder it counts it on (rotational velocity changes )
 

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:rolleyes: At least they're better than VAG. Any ECM that monitors radios and seat heaters needs to die.
 

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Discussion Starter #36
Copy that! I’ll deff remember all that. Gonna start trouble shooting soon and I’ll try to report to you guys if I find something.


Also another thing I forgot to mention but I
Sure y’all maybe already figure this. Sometimes while driving and it’s hasn’t happened in sometime the computer clears the code itself and the light goes off. So does that narrow anything else down since it seems to strictly happen only on startup.........sometimes?
 

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Discussion Starter #37
You can monitor rpm with the scanner and read the voltage at pin B with a voltmeter set to AC volts.

It will be a race for your eyes to see if the RPMS drops according to the actual engine rpms percieved by senses and if the ICM trigger signal drops out first and is causing it.

That is why a scope is handy because it charts both these readings IN REAL TIME, so its like a chart or graph you can easily see who drops out first by scrolling through the stored values.

Honestly I may just buy a scope. Can you recommend me one that you think is good for the price?
 

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Doesn't really narrow things down.

Codes are set after a certain threshold. If it reads a few voltage spikes it could be a blip in a reading and it would ignore it. After two or three blips, it sets a Pending code which just means that the code is stored, but it hasn't turned on the light yet. Then maybe after 5 logs of that high voltage it will turn the light on.

Then if the light goes away, it means that the condition hasn't been seen for a while. It depends on the system. In your case, it might go away after 15 more times that it hasn't seen the high voltage issue. In the case of an O2 sensor with a higher resolution, it might be 13,000 cycles that it doesn't report the condition before the light goes off.... which could be 10 minutes.
 

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48FordBigJob
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Many will change parts until they usually find something. My son is a mechanic and often gets jobs from other shops. His approach is similar to a criminal profiler. Give what is known to be facts without giving your opinions. He also has dealt with a lot of new, but bad parts and sensors. Corroded connections, bad grounds, voltage, chaffed wires, bad insulation from being probed and subsequently shorting or corroding are often things he finds often. The "Code is always right" gets expensive and change parts. Check basics.
 

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Many will change parts until they usually find something.
I had a self-defrosting refrigerator/freezer that the freezer was icing over. A 'parts changer' type came out from the local HVAC company and didn't have any diagnosis, was just going to change every easily changeable part and if that accidentally cured the problem for $200+ I would have a refrigerator worth $75 on the used market...
 
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