GENERAL DESCRIPTION - TM-9-2320-303-24-10187

WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

GENERAL DESCRIPTION

12.

ELECTRONIC CONTROL UNIT (ECU)

The ECU (Figure 13) contains the microcomputer which is the brain of the control system. The ECU receives and

processes information defining: shift selector position, throttle position, sump/retarder temperature, engine speed,

turbine speed, and transmission output speed. The ECU uses the information to control transmission solenoids and

valves, supply system status, and provide diagnostic information.

Each ECU has a date code stamped on the label which is attached to the outer case of the ECU. This is the date

when the ECU passed final test. This date is commonly used to denote the change configuration level of the ECU.

It is normal for the ECU date displayed electronically to be a few days prior to the date shown on the label.

NOTE: ECU wiring harness connector retainers

are individually keyed and color-coded to

ensure that the proper connector is attached

to the correct ECU socket. The color of the

connector retainer should match the color of

the connector strain relief (see Appendix E,

ECU

Paragraph 11).

V03352.01

Figure 13. Electronic Control Unit (ECU)

13.

SHIFT SELECTOR

Pushbutton and lever shift selectors for the WTEC III Series are remote mounted from the ECU and connected to

the ECU by a wiring harness. Both of these shift selectors have a single digit LED display and a mode indicator

(LED). During normal transmission operation, illumination of the LED indicator shows that a secondary or special

operating condition has been selected by pressing the MODE button. During diagnostic display mode, illumination

of the LED indicator shows that the displayed diagnostic code is active. Display brightness is regulated by the same

vehicle potentiometer that controls dash light display brightness. More information on both types of shift selectors

is continued below.

Pushbutton Shift Selector (Figure 14)

There is a full-function pushbutton shift selector and a strip pushbutton shift selector. Strip

pushbutton shift selectors are used by European OEMs. A full-function shift selector has a MODE

button and diagnostic display capability through the single digit LED display. The strip pushbutton

shift selector does not have a MODE button, diagnostic capability, or adjustable illumination. The

full-function pushbutton shift selector has six (6) pushbuttons which are R (Reverse), N (Neutral),

D (Drive), ⇓ (Down), ⇑ (Up), and MODE. Manual forward range downshifts and upshifts are made

by pressing the ⇓ (Down) or ⇑ (Up) arrow buttons after selecting D (Drive). The N (Neutral) button

has a raised lip to aid in finding it by touch. The MODE button is pressed to select a secondary or

special operating condition, such as ECONOMY shift schedule. Diagnostic information is obtained

by pressing the ⇑ (Up) and ⇓ (Down) arrow buttons at the same time. The strip pushbutton shift

selector has either three or six range selection positions as shown in Figure 14. When a strip

pushbutton shift selector is used, diagnostic information must be obtained by using the

Pro-Link 9000 or a customer-furnished remote display.