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Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 25350
Experience:  14 years GM dealer Technician.
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I'm working on a 05 Chevy 6.6 duramax my scanner said lost

Customer Question

I'm working on a 05 Chevy 6.6 duramax my scanner said lost communication with ficm I had the ficm rebuilt install and still the same thing
Submitted: 1 year ago.
Category: Chevy
Expert:  Pete replied 1 year ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
Inspect and see if any wiring damage is found leading to the FICM as this can cause this type of fault here.If an issue is found with any wiring the wiring will need repaired to correct this here.
Thanks Pete
Customer: replied 1 year ago.
I checked the whole harness it all looks good. Here is the whole story.I am working on a 05 Chevrolet k2500 with the 6.6 LLY
Issue is no start code u0105. Lost communication with ficm. The truck ran great as it was delivered to a body shop to have a dent repaired in the bed. The body shop called and said after the repair they could not get it to start. The car lot had it towed back to their shop and called me to look at it . My scanner gave me the code u0105 so I checked for voltage going into ficm and that was good. But I had no voltage coming out. So I sent the ficm to be repaired. They called and said they repaired  of few things that were wrong and sent it back. I installed the ficm and bleed the air out of the fuel system and cleared the code and it still will not start. And the code came right back. I called under the truck to see if maybe the body shop left off a ground and I noticed on the inside of the bed there were tack marks where they welded studs on to pull the dents. I'm wandering if they didn't unhook the batteries when they did the repair and fried something in the ecm?
Expert:  Pete replied 1 year ago.
O.k.,this can be common unfortunately.When welding is done if the battery is not disconnected ( as sometimes this can be forgot) this will damage one or more computers.If you trust the company you sent the FICM to then most likely the FICM is o.k. In some cases I have had repair centers send back the part saying it was repaired when it wasn't fully repaired.
The engine computer is the most likely suspect here with the FICM being o.k. as it communicates with it.I suspect it may have been damaged causing this here.
Thanks Pete
Customer: replied 1 year ago.
I sent the computer to be checked out and they said there was nothing wrong g with the computer
Expert:  Pete replied 1 year ago.
Are there any other computers that are not responding or communicating using your scan tool to check the computers?
Customer: replied 1 year ago.
No it all seems to work other than the ficm
Expert:  Pete replied 1 year ago.
O.k.,to be sure all power and grounds were checked to the FICM I will post them here.Double check to make sure these are all present and let me know what you come up with here.
In connector C1 locate the pink wire in terminal 5 and make sure it has at or near 12 volts with key on
Locate the yellow wire with black stripe in terminal 2 and test and make sure this has ground at all times key on or off.
In connector C2 locate the pink wire in terminal 119 and make sure it has battery voltage (near or at 12 volts) with key on
Locate the black wire with green stripe in terminal 114 and make sure it has ground at all times key on or off.
Thanks Pete