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boosted_diesel wrote: Thu Nov 06, 2025 8:51 pm

petem wrote: Thu Nov 06, 2025 12:51 pm

boosted_diesel wrote: Wed Nov 05, 2025 10:35 pm For them to function correctly yea they should be coded in.
It would probably run without the coding but not properly and at this point we don't want to introduce new problems. That's why we also change the seals to make sure there isn't a combustion leak created. Also you don't need to swap them back, you'll have learned what you need to after the first swap and there will be no further meed to swap anything unless you conclude the injector is actually faulty.

Good point - no need to swap them back. Either the code will move with the injector, indicating the injector is the fault or it will stay with cylinder 6, indicating a wiring issue. I'll try to get some new copper washers this weekend and if I can get my hands on them, I'll swap them out and let you know the outcome.

Thanks again for all your help and assistance. It is truly appreciated.

No worries, just bear in mind that if the code stays on that cylinder after swapping injectors then it is wiring OR pcm, as pcm is part of the circuit and is also the source. If it had a bad injector driver on the pcm pcb then it could do the same.

And I am *assuming* that bad injector driver = new PCM? I know they can be sent out for repair, but I don't believe I have anyone in my area that does that.

For what it's worth - when I delete the P1556 code, it does not come back until the truck is at operating temp. Not sure if that means anything, but I just thought I'd share that.

Thanks again!

petem wrote: Fri Nov 07, 2025 1:03 pm For what it's worth - when I delete the P1556 code, it does not come back until the truck is at operating temp. Not sure if that means anything, but I just thought I'd share that.

Thanks again!

Hey, yeah if a pcm driver is bad, then you can get it repaired by professionals. Many people will post them to a repairer if they are far away, they fix it and then send it back. Although you may wanna track post and have post insurance if you do this just in case it got lost or something.
On the other hand if you can't get it repaired then yes it would be a new one.

Well actually that is very telling! If it only does it when it fully heated then yeah you have discovered a piece of valuable information. You now know it only seems to happen under certain conditions, when it's fully heated. So you'll want to do oscilloscope tests etc under those conditions to increase the chance of being able to make the fault occur for testing purposes. It's another piece of the puzzle.

If it were me I'd be swapping injectors next.