on the LLY (your truck's engine name) Injectors 2, 3, 5 & 8 are on the same circuit. 2 & 8 are on the driver side and 3 & 5 are on the passenger side. They are opposing so that when the engine goes into limp mode, the engine is still relatively balanced and you can limp home. Injectors 2,4,6,8 are on the driver side and 1,3,5,7 are on the passenger side. P2149 refers to the 2nd bank of tied together injectors. 2,3,5,8 are also on the same connector on the FICM (fuel injector control module) which is on the passenger side, front, top of engine next to the alternator. When you get a P2149 code and all those others, you likely have an electical issue in that bank of injectors.
Some things you'll want to check. Pull of the connectors on the FICM and look for broken, corroded, bent male wire ends. Look for loose, corroded female ends. Then follow the wiring harness up to the top of the FICM and find where it is attached to the FICM, and check for shorts, worn wires. Then follow the wiring harness across the top of the engine and see if it is rubbed through anywhere it touches something, like the turbo mouth pipe. Then the next thing would be to trace the wires down to the injectors, looking for shorts. But the most likely issue you have is a loose connection at an injector. You can use the ice pick trick to tighten the female connectors in the injector connector. These diesels vibrate alot and it ends up loosening the female end. This is likely just an intermittent issue that can be corrected with the ice pick trick or replace all injector connectors.
You might want to go straight to the ice pick. The intent is to tighten up the female connector.
If the ice pick works, I would consider changing all injector connectors. If none of that works, you may need to open up the FICM and take a look. You will likely be able to see if it is bad, it's just a mother board. You can see scorching, expanded or burst, resistors, burn marks on the mother board, etc...
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