stumble and rough idle, dealer says no problem found

[delspeed]

so here's what happened, truck had been sitting in the cold for two days, started it up and let idle for a couple minutes, hopped in and drove off, around the 3rd gear upshift truck shuddered and cel came on, ran rough on four cylinders but made it to my shop, pulled codes 202, 203, 205, 208 and 1262, all four cylinders are on the same driver of the ficm, I'm thinking ficm, called gm store talked to diesel tech, he says injectors. tow it 20 miles on trailer, drive it in running like crap shut it off, tech comes out and starts it and it runs fine, he's been driving it for two days and it hasn't had a problem. I'm still thinking ficm but could be a harness problem I guess also.

[Duramaster]

What year truck and what engine? LBZ, LMM, LLY or LB7?

[delspeed]

02 duramax 121000 miles.

[Duramaster]

It's probably not the FICM. Check the wiring harness for chafing at the FICM where it is tie strapped to the FICM bracket. I have had several vehicles with the same issue which all boiled down to chafed wiring. ;)

[DmaxMaverick]

Same here. I lost a bank and it turned out to be a chafed wire in the harness, off the FICM, in the plastic loom above the FICM. It was intermittent at first (enough so I couldn't find it at first), then was more often. Turns out, my aftermarket fuel hose put pressure on the harness (just laying across it), and caused the harness to chafe. Easy to see once you know it's there.

[Duramaster]

I usually end up repairing the chafe of course, then I take my "WIZZIE WHEEL" ( mechanic term for 90 degree die grinder with a 3M scotch brite pad attached) and raound the sharp edges off of the FICM bracket. I also wrap the hatness with spiral wrap. :::hint hint:::

[delspeed]

Update, I got the truck in the shop this morning, it has been running fine all week, pulled the harness up off of the ficm bracket and no chaffe checked all over the top of the engine and found no chaffe anywhere? unless one injector could short and kill the whole driver I'm thinking the driver in the ficm went out in the extreme cold.

[delspeed]

today started the truck up and headed out the driveway, have driven it a few times this week with no problems, hit a bump and it shut off like I flipped the switch and now will not start just spins over, I checked for air at the filter by backing off the bleed screw and all I got was fuel. I should add that after the stall the cel would not come on w/ the key on. after it sat for awhile the cel did come back on but still no start.

[madmatt]

At least the dealer can't say nothing is wrong w/ it now!!!!!!!!!

[Dakster]

Madmatt,

I can tell you are one of those glass half full people. (always the optimist).

Delspeed any luck on the diagnosis?

[madmatt]

Yes I am!! The way I look at things is that if I'm still breathing,,,,, it could be worse! It took me nearly having a mental breakdown from worring about things to realize that though!

[delspeed]

got the solus on i the other night, pcm has a u1800 in it no comm. with ficm, checked the fuse, good, didn't have my dvom to check power and ground at the module but I am almost certain at this point that the ficm has taken a crap on me. does anybody sell them aftermarket? our sister dealer says my cost is 577 on it ouch. I'd hate to have to pay the over a thousand list.