Vehicle: 2014 Audi Q7 Quattro (4LB), V6-3.0L DSL Turbo (CNRB), automatic transmission
Problem: The transmission would not upshift from low gear.
Details: When the technician connected a scan tool, he found 20 communication DTCs listed in various modules because they could not communicate with the Transmission Control Module (TCM). Using his scan tool, he verified there was no communication with the TCM.
The first thing the Tech-Assist consultant advised was to check power and ground circuits to the TCM. The technician found that the green/red power wire at TCM pin #27-28 did not have battery voltage. The #5 fuse was good and had full voltage to it. The technician noted that the green/red wire ran under the door sill plate and the carpet had signs of water damage. He opened the harness insulation and found the green/red wire has broken due to corrosion.
Confirmed Repair: The technician stripped the wire insulation back to where the wire strands were clean, soldered in a new wire, and used heat shrink to seal it back up. After the repairs, all the codes were cleared and the vehicle test driven. The transmission shifted normally, and no DTCs returned.