Need help tried all the easy stuff

[bigred4500]

I bought a 03 chevy 4500 with duramax diesel 6 months ago it smoked a little when idling but run good. Wasn't long went to get it inspected and it went in to limp mode so we took it back home checked the codes said it was a bad injector wire left it go that night next morning it was fine ran it about a month went back in to limp mode again. then we ohmed all the injectors they were good checked batteries-good checked connections-good fuel filter-good fuel vacuum-good traced wires all were good. 2 injectors are at a 6 on balance rates. So we replaced the FICM ran good for another 250-300 miles. Thought we had it fixed NOPE it went into limp mode again. Checked all the wires again and the next day it ran fine but it is showing codes: P0201 P0204 P0206 P0207 P0523 P1261.
I Dont want to keep throwing parts at it I plan on replacing Injectors but want this problem fixed first. Also it just started when i turn the key off it wont shut the ac blower off. Not sure if that related but that just been the last few days. I cant trust the truck so i need it fixed please help.

 

[btfarm]

You might look here:http://ww2.justanswer.com/uploads/Bluegorilla/2011-03-01_192216_lly_connector_update.pdf
Later MDs had LLYs and the injector connectors had issues. Try searching for "ice pick" repair also.

 

[Chevy1925]

You might look here:http://ww2.justanswer.com/uploads/Bluegorilla/2011-03-01_192216_lly_connector_update.pdf
Later MDs had LLYs and the injector connectors had issues. Try searching for "ice pick" repair also.

an 03 isnt gunna have a LLY in it unlesss it was swapped out to one

 

[btfarm]

an 03 isnt gunna have a LLY in it unlesss it was swapped out to one

Thus the "later MDs" comment. But the connector issue on MDs could have come along earlier.

 

[RKTMech]

You probably have a loose connection or wire chaffe issue from the sounds of it. Look for areas where the wire cover has degraded and rotted off for wire chaffes. Inspect for backed out wires in the big bail conectors on the driver side of the engine. Here is a good Document ID: 2327612 has some pics, Sorry I dont know how to transfer it here properly, here is another one Document ID: 1828652 Good luck wire issues can be tough.

 

[bigred4500]

I've chased down every wire I could see.
What's everyone think about a new wiring harness and replacing the injectors in the heads there might be shorts thanks for all the help let me know what you think

Thanks