General Description

Until recent years, hydraulic and mechanical devices had been the only controls used for transmission power and logic functions. Transmission designs have become more complex: from the three speed Ford-O-Matics, with limited hydraulic and mechanical controls, to the current E40D, AXOD, and A4LD which have electronically controlled automatic shifts and converter lock-up clutch controls.

As an example, on conventional non-electronic transmissions when a concern of no 1-2 shift was encountered, there was a good chance the governor valve was sticking or stuck. Freeing up the governor valve would correct the concern. The E40D does not have a governor.
A no 1-2 shift could be caused by one or more of engine or transmission sensors or solenoids. The sensors and solenoids can only be diagnosed by using the Star Tester.

In the past, system quick testing could be used to diagnose converter clutch lock-up concerns on transmissions such as the AXOD. However, the E40D transmission has shift functions, coast clutch control, electronic pressure control, and lock-up functions all controlled by electronics. When performing diagnosis on an E40D transmission, you must first perform the system quick test to make sure you check all possibilities of a particular condition. An apparent mechanical or hydraulic concern may be caused by electronic conditions. Even if you service a mechanical concern, make the necessary checks on the electrical systems as well. Also be aware there are certain transmission electronic symptoms which may cause engine performance and driveability concerns.

For gasoline engines, the control center of the E40D is the EEC IV Electronic Control Assembly (ECA) processor (12A650). For diesel engines, it is the transmission Electronic Control Assembly (ECA) processor (12B565).

On gasoline engines, the ECA contains both the transmission and engine strategy/software. On diesel applications, the transmission ECA is a stand alone unit providing electronic transmission control only. In either case, the ECA processes input signals from various sensors which provides information on a variety of operating conditions. The ECA then provides shift scheduling, converter clutch scheduling, shift quality and line pressure control by activating the proper solenoids.

OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 590000