15396B - Service Update (Parts Information revised). This bulletin provides a service procedure to install the original design temperature-sensor wiring harness to the valve body on certain 2015 model year Cadillac Escalade and Escalade ESV; Chevrolet Silverado; and GMC Sierra, Yukon, and Yukon XL vehicles, equipped with a 6.2L engine (L86) and 8-speed automatic transmission (M5U). The supplier of the transmission-wiring harness introduced an unapproved change to the temperature sensor (thermistor), resulting in incorrect oil-temperature readings during transition from cold to warm temperatures. This could cause a harsh shift when starting the vehicle at temperatures below 32ºF (0ºC); however, shift quality improves once the transmission oil warms up.
