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Im getting u1800 u2104 u2106 codes on my 02 chevy duramax…

Im getting u1800 u2104 u2106...
Im getting u1800 u2104 u2106 codes on my 02 chevy duramax its shifts at high rpms
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Answered in 21 hours by:
3/13/2018
Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 5,694
Experience: ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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This code indicates a communication issue between the ECM, TCM, and FICM. If you have oil in the TCM connector at the transmission, that needs to be corrected, there should be no oil inside this connector. These communication circuits are very sensitive to things like this, if there is any path to ground or to each other, the communication gets interrupted and you get these codes.

If these CANBUS circuits are good, not touching ground, etc. then one of those three modules has failed. You replaced the TCM, I assume to address this issue and it didn't change it, correct? ECM and FICM are the only other two computers on this circuit. Both have a pretty healthy failure history, so it's a crapshoot which one to replace next.

But I would definitely be very vigilant about looking at these wires. The transmission was out of it recently: did the wiring get damaged, even just a little bit, causing this issue? All that needs to happen is for one of the two communication wires to just barely touch ground anywhere, and the comm circuit is dead, and you get these codes. Invest some time in this harness and wiring and make sure it's dead perfect. If you are certain about these circuits, only then would I replace another module.

I'm attaching some schematics that show the circuits and where they run.

Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 5,694
Experience: ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
Verified
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Jerry Newton, Chevy Technician
Category: Chevy
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Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

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