6.6L duramax question

4x4dually

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Guy at work sent me this. I know jack schit about not duramax. Any advice?
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Around the farm we have a 2003 Silverado with a 6.6L Duramax, completely stock, still has the original injectors which are supposedly problematic. A few weeks ago, after a short drive, it was turned off and then hours later when we went to restart it, it would not even attempt to start (crank, no start, no hits, like the injectors were not activating at all).

Usually when we have situations like this it is air in the fuel filter housing, but there was no air. I used an OBD tool to look for clues, but there were no codes or pending codes. When cranking the fuel rail pressure went to ~7000 psi. I began inspecting and reseating various connectors, one of which was the FICM, but that yielded no improvement. We checked all fuses, no issue there.

In a last ditch effort, I disconnected both batteries and we left the truck overnight. The next day, we reconnected them and it immediately started and has been fine ever since. This is a concerning because who knows if it will happen again, still no codes or issues reported by the PCM.

I don’t think it was the FICM, as there was no error codes and I disconnected it for about a minute, so it should have reset if the MCU in it froze.

It may have been the PCM, but it was willing to talk to the OBD reader and was reporting all the sensor data, so it doesn’t seem like it froze.

Security system possibly malfunctioned?

Any thoughts, besides carry a side post battery wrench in the glovebox?
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Thanks in advance for any ideas.
 
Double check the three or four ground straps between body and chassis.

Also, I have seen this happen when the big cam Lock connector on top of the motor looses connection slightly.

Not a duramax wizard but have worked on a few...
 
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