Hello, new to the forum and diesels, great info found here so far.

I have an 04.5 LLY with 268,000 miles, I have only owned it for the past 3,000 miles. Truck ran great for the first 1,500 miles I had it, however for the past 1,500 miles its running terrible and I cannot for the life of me figure out whats wrong.

In the morning when it's cold out the trucks runs ok, however within minutes or driving, once it's warmed up, the engine begins cutting out and knocking really bad. CEL has come on a few times and has thrown a P1244 and P0308, but not always.

I had a buddy with EFI live check the balance rates on the injectors and all were within spec.

So far I've tried: Ice Pick #2, #7, and #8, did not fix, then I bought the GM harness repair for #2, and #7, and new connector for #8, did not fix, I've searched the harness for rub through and found none, but put rubber hose on spots that had evidence of any rubbing anyway, did not fix, replaced the fuel filter, still same problem. Also replaced both batteries to no avail.

Sorry for the long post, however not quite sure where to look next as I have exhausted all my theories. Any help or ideas would be very much appreciated. Thanks. :)

fuel filter?

sorry re read and see you replaced it. i guess i would guess that or fprv

after all that stuff you are still getting the #8 failure? I'd look at the FICM...drivers side near the firewall. (Fuel Injector Control Module).. make sure you don't get water on it, like after power washing the engine or something, they are sensitive to that stuff.

after all that stuff you are still getting the #8 failure? I'd look at the FICM...drivers side near the firewall. (Fuel Injector Control Module).. make sure you don't get water on it, like after power washing the engine or something, they are sensitive to that stuff.

Will check that connection today.

Any updates, I am having the same problem.

after all that stuff you are still getting the #8 failure? I'd look at the FICM...drivers side near the firewall. (Fuel Injector Control Module).. make sure you don't get water on it, like after power washing the engine or something, they are sensitive to that stuff.

Now I may be wrong, but I thought the FICM was mounted on the passenger side valve cover, behind the Alt.?

Any updates, I am having the same problem.


I tried cleaning all the connectors, still no luck yet. I will continue trying to pinpoint the issue.

Any updates, I am having the same problem.

disconnet your bale connetcors on top of the motor spray with electrical cleaner really good reconnect should do it.

had any luck finding the problem? im having the same problem on my LLY

This is for the guys that do not know about this LLY problem--Inspect the FICM wire harness at the passenger side of the alternator. The harness and wires get cut, and sometimes short to ground, by contact with the sharp corner of the FICM bracket.

The harness is tied down with a zip tie, cut the zip tie and look carefully at the under side. Insulate with a piece of heater hose.

This is a common problem for the LLY engine. Everyone that has a LLY should check this now!