NHTSA Complaint #11424230 — 2019 GMC TERRAIN

*The service transmission message coming on and the vehicle goes into neutral and stalls, service transmission light comes on while on highway and the vehicle goes into park and loses power and stalls, All wheel drive message coming on, traction light coming on, going about 74 mph on highway and speed gauge dropping, low fuel light coming on even thought it has 3/4 tank of gas. *I almost got ran into from behind twice when the vehicle went into neutral and into park by an 18 wheeler truck as I was trying to pull over onto the shoulder of the highway. *Confirmed by LaFontaine in Ann Arbor, MI *Vehicle has been inspected by LaFontaine in Ann Arbor, MI. Found bulletin 19-NA-181 which was very close to all symptoms and stated to check for chaffed wires near the ECM. Found no spots in the tape where it was rubbed through but lost comms when wires were shook. Unwrapped main engine harness loom and inspected wires, found nothing. Started TAC Case # 9-6385087421 and was told it probably is a chaffed comms wire somewhere and gave me multiple locations to check. Found no damaged wires in those locations and shaking main harness no longer would make it fault. Put it all together and drove it down the road and faulted immediately. Unwrapped main harness again snd sprayed with saltwater to help conductivity but still couldn't get it to fault while shaking the harness. Only way it will fault is when shifting into drive the drive train bumps just right to bend the right wire. Checked every wire I could find and can't find the problem wire. Not drivable. When this vehicle faults it will not shift past 1st gear and sometimes locks out reverse. Must be towed. Needs the main wiring harness to start, recommend customer to authorize FSE to dealership CUST declined. *Yes, all the lights and messages were coming on over the dash.