WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL GENERAL DESCRIPTION 1–2. ELECTRONIC CONTROL UNIT (ECU) The ECU (Figure 1–3) 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, Paragraph 1–1). BLACK BLACK GRA GRA Y BLUE BLUE BLUE BLUE V03352.01 ECU Figure 1–3. Electronic Control Unit (ECU) 1–3.
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. All shift selectors except the strip-type pushbutton 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 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. MODE A. Pushbutton Shift Selector (Figure 1–4) button and diagnostic display capability through the single digit LED display. The strip pushbutton shift selector does not have a There are two full-function pushbutton shift selectors and a strip pushbutton shift selector. Strip pushbutton shift selectors are used by European OEMs. A full-function shift selector has a MODE button, diagnostic capability, or adjustable illumination. The full-function pushbutton shift selector has six (6) pushbuttons which are MODE R (Reverse), N (Neutral), .
Manual forward range downshifts and upshifts are made by pressing the D (Drive), (Down), (Up), and MODE (Neutral) button has a raised lip to aid in finding it by touch. The (Down) or (Up) arrow buttons after selecting D (Drive). The N button is pressed to select a secondary or special operating condition, such as ECONOMY shift schedule. Diagnostic information is obtained by pressing the MODE (Down) arrow buttons at the same time. The strip pushbutton shift selector has either three or six range selection positions as shown in Figure 1–4.
When a strip pushbutton shift selector is used, diagnostic information must be obtained by using the ATDT TM , Pro -Link ® 9000, or a customer-furnished remote display. (Up) and Copyright © 2001 General Motors Corp.