Some 2019 Silverado 1500, Sierra 1500; and 2020 Silverado and Sierra models may have a discharged battery, the ignition may not turn off, a Shift to Park message may display on the Driver Information Center and the Check Engine light is illuminated. There also may be a lack of communication with the K71 Transmission Control Module (TCM) and E20 Engine Control Module (ECM) along with one or more of the following DTCs set in the TCM: U007B, U0100, U0101, P0658, P0707, P2803, P0712, P07BF, P0722, P077C, P0960, P0962, P0964, P0966, P0968, P0970, P176C, P17CC, P2670, P2718, P2720, P2727, P2729, P2736, P2738, P2812, P2814, P281B, P281D, P2824, and/or P2826.
These conditions may be caused by the TCM connector not being seated and latched properly, resulting in poor terminal connection from the TCM to the engine harness. The TCM connector is a multi-wire electrical connector, which can set a variety of DTCs. Different conditions and driver notifications may be caused by one of the terminals in the electrical connector not coming into contact with the pins in the module. Components on different lines are in different circuits. Due to the cause of the condition, and the positions of the wires in the connector, it is unlikely that more than one circuit will be affected by the condition.
Inspect the K71 TCM connector for proper seating. An initial inspection may show that the connector is cocked or high on one side of the connector body. (Fig. 29)
Fig. 29
One of the lever lugs on the TCM connector may be coming out of position on the horizontal sliding lock bar, which may cause the drive lug to slide along the outside of the locking bar. (Fig. 30) Operating the lock lever may show that the lock is not moving properly.
Fig. 30
To correctly install the TCM connector, place the connector onto the TCM and squeeze the connector lever lock housing to ensure the lock bars are moving into the proper position on the TCM connector body. (Fig. 31)
Fig. 31
– Thanks to David MacGillis
