TM 9-2320-366-34-1
1-10. POWERTRAIN (CONT)
Figure 1-12. Powertrain (Cont)
a. Engine. The vehicle is equipped with a Caterpillar diesel engine, model 3116 ATAAC (Air-to-Air After Cooler) (1,
Figure 1-12), rated at 290 HP.
b. Transmission. The vehicle is equipped with an Allison automatic transmission, model MD3070PT (2, Figure 1-12).
It is a fully automatic electronically controlled seven-speed close-ratio transmission.
(1) The WTEC II TEPSS contains microprocessor based electronics, and is located in the instrument panel to the
driver’s left. The WTEC III TPSS is located in the instrument panel to the driver’s left, while the WTEC III
transmission ECU is located behind the kick panel. The ECU receives information, in the form of electrical signals
from the various sensors, processes that information, then sends the appropriate signals to the solenoids which
control transmission function. The ECU incorporates a diagnostic program which enables it to identify numerous
actual and/or potential transmission problems. The WTEC II TEPSS and WTEC III TPSS are capable of displaying
diagnostic codes in the Light Emitting Diode (LED) display on the pushbutton shift selector. These diagnostic codes
are stored in the ECU for later retrieval. The pushbutton shift selector is used for selecting transmission range. The
transmission defaults to Neutral (N) whenever electrical power is removed from the vehicle. The Drive (D) gear
selection is used for normal driving conditions. The transmission will engage 2nd gear when D is selected and the
vehicle is stopped. As the accelerator is depressed and speed increases, the transmission will automatically upshift
through 3rd, 4th, 5th, 6th, and 7th gears. Low gear (1st gear), is available only by manual selection. Selecting a
specific gear; for example, 3rd; will prevent the transmission upshifting past the selected gear. This is useful if road
or load conditions require lower gear range operation. When road conditions improve or load is reduced, the shift
selector can be returned to the normal (D) driving position. When electrical power is applied to the WTEC II TEPSS
and a fault is detected in the transmission controls, the WTEC II TEPSS will emit an eight second series of beeps.
When electrical power is applied to the WTEC III TPSS and a fault is detected in the transmission controls, "--" will
appear in the WTEC III TPSS LED display. In either case, the transmission will not engage a range (forward or
reverse) when D or Reverse (R) range is selected on the pushbutton shift selector. TM 9-2320-366-10-1 provides
full operating instructions for the transmission.
(2) The transmission may include a Power Take-Off (PTO). The PTO powers a hydraulic pump which supplies
hydraulic pressure for hydraulically operated components.
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