WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL GENERAL DESCRIPTION Copyright © 2001 General Motors Corp. 1–11 Even after autodetect has been completed, it can be reset to monitor an additional group of engine starts. Reset may be necessary if a device known to be present is not detected or if an autodetectable component or sensor was added after the initial vehicle build. Reset is accomplished by using the ATDTTM or Pro-Link®.
Using ATDTTM, select “RESET UNADAPTED SHIFTS.” Using a WTEC II Pro-Link®, select “RESET TO UNADAPTED SHIFTS.” Using a WTEC III Pro-Link®, select “RESET AUTODETECT.” The ATDTTM or WTEC III Pro-Link® can also be used to override autodetect and manually enter the component or sensor to be recognized by the ECU by changing appropriate “customer modifiable constants”. The four items above are the only customer modifiable constants (CMCs) that are autodetected. Other CMCs can be changed at any time and are not related to autodetect.
Consult the ATDTTM User Guide (GN3433EN) or the WTEC III Pro-Link® manual for detailed instructions related to WTEC III “customer modifiable constants.” Additional details for each of the four autodetectable features are given below. A. Retarder Autodetect searches for the presence of the H (retarder) solenoid during the first 24 engine ignition cycles. The H solenoid must be present on the 24th engine start or the retarder is not detected and will not function on subsequent engine starts. WARNING! If a retarder is present but is not detected by autodetect, the retarder will not function. Be sure to check for proper retarder function immediately after the 24th engine start.
If the retarder is not functioning, check H solenoid for open, short- to-ground or short-to-battery condition. Use ATDTTM or Pro-Link® to reset autodetect or to manually select the presence of the retarder after the H solenoid circuit is repaired. B. Oil Level Sensor (OLS) NOTE: If an OLS is known to be present, but has not been detected, a possible cause is that the transmission fluid level is too low. Check the fluid level before beginning OLS troubleshooting. No oil level sensor diagnostics take place until the OLS is detected. Frequently check for the presence of oil level diagnostics if the transmission is known to contain an OLS.
If an OLS is not detected during the first 24 engine starts, autodetect continues for a calibration number of engine starts. Autodetect stops when an OLS is detected or when the calibration number of starts is reached. When the calibrated number of engine starts is reached, the ECU concludes that no OLS is present. If an OLS is known to be present, but has not been detected, troubleshooting of the OLS circuit is required. After the OLS circuit is repaired, reset autodetect or manually select the OLS function using the ATDTTM or Pro-Link®. C.
Throttle Source (V8, V8A Software — See Paragraph 1–9C for V9 and 9A) Whenever autodetect is functioning and no throttle source is found, a code 26 00 is logged. If a datalink throttle source (J1939 or J1587) is detected, autodetect stops looking for that function. However, if no analog throttle source was detected prior to engine start 25, autodetect continues for engine starts 25 through a calibration number. Autodetect for analog throttle stops as soon as a device is detected or when the calibration number of starts is reached. If an analog throttle source is known to be present, but is not detected, troubleshooting of the analog throttle circuit is required.
After the analog throttle circuit is repaired, reset autodetect or manually select the analog throttle function using the ATDTTM or Pro-Link®. An engine throttle source must be present. A PWM throttle source requires a unique calibration or must be manually selected using the ATDTTM or Pro-Link®.