I had that problem. Then kept having it. They replaced entire wire and ground. Home, 50 miles, back to limp mode and back to the shop. Swapped FICM, still in limp mode. Turns out fuel injector itself went bad and shorted out. Shop said they never seen that before. No one on internet has ever had this problem that I could find. And the shop is a former GMC dealership and I have known the main mechanic (and part owner) for probably 35 years. So if they haven't seen this problem, it's rare. I just hope this helps someone else.
I don't know if I ever commented but further down the harness it had rubbed through the plastic shield and through one of the ficm wires on the metal injector line
This wire leads to either number 2 or number 7 injector. Replace the wire by buying pigtail and splicing a longer piece to it. It sounds like that because it threw your truck into limpmode because you lost an injector
I had/have this same problem right now in my 04.5. Mine had a short in a bare wire at the spot where the harness crosses over the bracket up front, too. My mechanic caught that and fixed it. But it still ocassionally is kicking into limp mode, usually the day after I've driven it long distances and sometimes hauling trailers or equipment. I'm pretty certain Jaime is right. I'm getting ready to replace a pigtail after I get off here. My problem is, it's running right and no matter which connecter (2 or 7) I wiggle, it won't start clattering! But, yeah, the rubbed-bare wire was taken care of, and was probably part of the problem. But I've seen too many youtube vids that show the connecter wires to be the culprit. I agree with Jaime Cornejo here.
When this happened to you guys, did you experience more black smoke than usual? Think this might be happening to my lly, seems to happen after long cruises down the interstate at random the past few weeks
sounds like #2#7 ,what guys call the ice pick repair,common issue in lly,the repair is a new injector connector w heat wrap,bolt on bracket, mine did it twice ,looks like in this video when you move the wires causing a disconnect in the circuit,which throws the code ,merchant auto sells a cinnector kit, or amazon or eBay ,....so did you find a wore out wire from vibration or chaffing,....thank you
Yes I commented down lower, down the the main harness the line it had rubbed through on the metal injector line, the size of a pin hole I cut the section out and added new, with heat shrink and it was fixed. And yes I had the problem you speak of before I went down this road.
@@jackdearcop8363 I kept opening the wire loom and shaking wires around while the engine was running until it would cut the injector out, I kept doing it until I narrowed it down to a little hole near the left injector steel fuel line, be careful though there is high voltage in those injector wires. I used a stick to poke around
Yep were I have those wires open in the video, a bit further down towards the engine it had rubbed through the harness loom against the injector line and made a small pinhole in one of the wires, I cut and spliced it and it fixed the issue, I then used rubber radiator hose around that area to make it more durable also around the ficm, this fixed my issue before this I replaced pigtail harness one cyl number one a well which was another problem i was having.
Question when you cut the yellow wire did you have 2 wires in one like a ground and the regular wire looks grey in color with yellow casing ??? I think I have the same issue thx
Never cut it open, just opened the harness up by the ficm followed it down, and one of the wires had rubbed through against an injector line below I cut the wire and spliced it back together
Jp Fecteau yeah you have an lb7 its a bit different from an lly see i started by changing my injector pigtails ( which didnt help) which i think yours are under your valve cover mine are not then i moved to the ficm area which is a problamatic area for an lly but i had already ruber hosed the line to the alternator bracket, i stripped the loom all open opened the casidng over the egr and wiggled each line and tested them then i finally saw the wire right by the high pressure injector line if you look in the video where i push on the harness its where you can see it going down under the egr right there the loom was worn though against the high pressure line and a tiny tiny pin hole on the yellow wire i cut it out and soldered it back together and then melted a piece of heat shrink over it
Crimped with a crimp connector and shrink wrapped the line Where it was rubbed through, the other line I soldered and shrink wrapped it, tied it all back up wrapped radiator hose around it.
