Test Port: The Allison 1,000 transmissions have a port on them called a "Diagnostic Pressure Port." This port was designed for transmission companies to test line pressure inside the transmission. The test port is located on the Transmission Bell Housing, near the external screw-on filter. This item can be found on our website under transmission adapters.
Cooler Line: Another method of installation would be to install a "T" fitting onto the cooler line to get a reading of the fluid going to the cooler. This installation method will give you the reading of the fluid exiting the trans and going to the cooler to be cooled down before returning to the transmission. On the Allison 1,000 Transmission, the cooler line size if ⅝. Glowshift specifically designed a T-fitting for this size line and can be found on our website under transmission adapters.
On average, the Diagnostic Pressure Port is going to run a cooler temperature than the Trans Cooler Line. When we tested on our stock vehicle, it can be up to 35 degrees in difference.