A/T - 43DE/A43DL Differences

SIL 87-26 (Aug.)

SUBJECT: A 43DE/A 43DL The Difference

COMMONLY USED ABBREVIATIONS AND THEIR MEANING:

Hydraulic Control Unit Valve Body
Electronic Controlled Unit ECT
Electronic Control Unit ECU

The A43DL is a hydraulically controlled transmission. Shift control in A43DL is accomplished hydraulically, as follows:

1. The governor valve generates hydraulic pressure in proportion to vehicle speed. This pressure acts as a vehicle speed "signal" to the hydraulic control unit (valve body).

2. A throttle valve in the hydraulic control unit generates hydraulic pressure in proportion to throttle opening. This pressure acts as a throttle position signal to the hydraulic control unit.




3. The two varying pressures act upon, and control shift valve movement in the hydraulic control unit. These shift valves direct hydraulic pressure to clutches and brakes, which perform shifting of the transmission. (See figure 1)


Shift control in the A43DE is performed in a different manner.

1. The vehicle speed is monitored by the vehicle speed sensor, which sends the data to the ECU in the form of electrical signals.

2. The degree of throttle opening is sensed by the throttle position sensor, which transmits data to the ECU in the form of electrical signals.




3. The ECU determines the shift point on the basis of these two signals, and operates the solenoid valves in the hydraulic control unit, thus shifting the transmission. (See Figure 2)

4. The electronic controlled system provides shift point control only when the vehicle is moving forward. In reverse, park and neutral, the transmission is mechanically, not electronically, controlled.

5. Mainline pressure control in the ECT is totally independent of the electronic shift control circuit. Therefore, when mainline pressure drops for any reason, the ECT is subject to the same problems as the hydraulically controlled transmission. Improper throttle cable adjustment may result in shift complaints unrelated to the electrical controls.