2017-19 GM trucks with Allison transmissions utilize an auxiliary transmission cooler thermal bypass valve to control fluid flow to the auxiliary cooler. The factory valve is restrictive and does not allow sufficient flow to the auxiliary cooler causing higher trans fluid temps especially on trucks with increased line pressure from trans tuning or a built trans. This bypass valve has seen a 50 degree temp drop, even on stock trucks, and have had customers reporting 60 degree temp drops. This design allows you to install the factory thermostatic valve for cold weather operation to maintain optimal fluid temp year round. Install time is less than 10 minutes. This valve is a must for all 2017-19 diesel GM trucks.
