Aisin Seiki’s six-speed transmission used in medium-duty trucks is called by various names. It is the AS68RC in Dodge incomplete-chassis packages using L6 6.7-liter diesel engines. It is also called the AS6 in the Mitsubishi Fuso, the M036A6 in Nissan UDs and the A465 in Isuzu NPR trucks.
One of the common failures with this transmission is the stator turning in the pump (figures 1 and 2). A similar problem occurs with Allison 1000/2000 transmissions, in which it causes a TCC overheat and/or C1-clutch failure. You can quickly determine this by pulling the return cooling line. Oil comes out of the case fitting instead of the cooling line.
We have had some confusion on the ATSG help lines in reference to 1999 and later Mitsubishi Fuso tilt-cab medium-duty trucks equipped with the Aisin Seiki.
The first problem is, how do I get codes out of these trucks? Since aftermarket scan tools do not communicate with these trucks, data is not available and code retrieval must be done via the flash-code method. That means that a certain procedure must be performed, after which a light somewhere on the dash will flash a code pattern. The illustration in Figure 1 shows the locations of the diagnosis switch and the memory-clear switch, both of which are single-pin connectors.