Sorry for the mis-information on my last thread. I am going to start from the beginning again.
I am having an issue starting my truck (2007 F250) since it got cold out this year. I have no issues if it is plugged in but it won't hardly start if it is cold. I finally got some time the other day to run a scan on it with my scanning program and it initially had errors ( The P067x codes) on cylinders 1,2,3,4,5,6,8. I did a quick check on the ODD bank and all the plugs checked fine checking at the pigtail for the harness ( small black 4 pin plug) I got a range from .2 - around 1.0 ohms. According to what I have read that should be fine. I did not check the drivers bank at that point as I figured since 1, 3 and 5 had codes then I should have seen something show up there. At that point I got ahold of a new GPCM, since from all the info I had read that is likely what would cause the issue. No improvement other than after clearing the codes and cycling the plugs a few times I got codes for 1,2,3,4,5,6 and 8. For whatever reason plug 7 was not getting the code now. Whatever. I still had codes off both banks so I was a bit confused. That is when I posted my previous thread.
So today, I had some time finally to really dig into it deeper. I had spent some time going over what you guys had told me in the previous thread and then scoured the internet for some more info as well. I now have traced my wiring and checked everything at the small black plugs and then checked the resistance from the GPCM plugs to the plugs for the glow plug harnesses.
I checked the GPCM plug connectors and they all look perfectly clean and nice and tight. I then checked the resistance from the GPCM plug to the plug for the harness and got pretty much no resistance on any of the wires. So that should be good.
Next I checked ALL of the plugs through the harness plug. Here is what I got.
1 - 0.2 ohms
3 - 0.4 ohms
5 - 0.4 ohms
7 - 0.8 ohms
2 - 25.3 ohms
4 - 16.6 ohms
6 - 11.9 ohms
8 - 0.2 ohms
So then it would appear that plugs 2, 4, and 6 are bad. However I am still questioning why I would be getting codes on all of them beside 6, and 7 now. I think 6 is technically on the verge of being out of spec so maybe on just a couple of cycles it worked ok enough to drop out of the codes? But still I was getting codes on all of the good plugs except 7. So even though I may have an idea of what plugs are bad, I am still confused. I am also wondering if there is a chance I have an issue with the harness on the drivers side itself since I have only had the plugs in and the new harnesses on for less than 10,000 miles. Maybe a defect? But even at that, why the codes on the other bank?
While you experts mull this over and hopefully give me some next step advice I am going to go pull the wires off the plugs on the drivers side for now and see what kind of readings I get at the plugs themselves. Hopefully I won't break them, they aren't too old and I do have the puller tool.... but I know how well the old ones came out.
Again Thank you all in advance for the help. I actually sort of enjoy working on this thing myself.