Checking the fluid level on any vehicle equipped with Ford Motor Companys new 5R55N transmission may become confusing to some technicians. There is a plug in the extension housing, as shown in Figure 1, that would lead one to believe that this is where you check the fluid level, since some of the other manufacturers are currently checking fluid level in this manner, and it refers to the correct temperature to check the fluid right on the extension housing.
However, this is a “Fill” plug only on the new 5R55N transmission from Ford Motor Company, which is currently found in the 2000 Lincoln LS and some Jaguars. To “Check” for the correct fluid level, you must remove the check plug, which is located in the center of the bottom pan drain plug, and is removed with an allen wrench, as shown in Figure 1, while holding the drain plug with the proper size wrench so as not to loosen the drain plug.
We have provided you with a cut-away drawing of the bottom oil pan and the drain plug so that you will understand how this system works. Notice that the drain plug actually has a “stem” made on it that extends some distance up into the bottom pan, which is our way to establish the proper fluid level in the transmission. By removing the “Check” plug from the “Drain” plug, the fluid should just trickle over the stem and out through the center of the drain plug, as shown in Figure 1. The “Fill” plug in the extension housing is your only way to replace fluid in the transmission.