WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL BASIC KNOWLEDGE Copyright © 2001 General Motors Corp. • Inspect all connector terminals for damage. Terminals may have bent or lost the necessary tension to maintain firm contact. • Clean dirty terminals or connectors with isopropyl alcohol and a cotton swab, or a good quality, non- residue, non-lubricating, cleaning solvent such as LPS Electro Contact Cleaner® or LPS NoFlash Electro Contact Cleaner®. CAUTION: The cleaning solvent must not be chlorine based, contain petroleum distillates, or conduct electricity. The cleaning solvent should evaporate quickly to prevent the possibility of condensation within the connectors.
Always blow or shake any excess cleaner from the connector before assembling it to its mating connector or hardware. Cleaner trapped in the connector can affect the connector seal. (Refer to SIL 17-TR-94 for detailed information on the recommended cleaners.) CAUTION: Care should be taken when welding on a vehicle equipped with electronic controls. Refer to Appendix G, Paragraph 1–1. • Diagnostic codes displayed after system power is turned on with a harness connector disconnected, can be ignored and cleared from memory. Refer to Section 6, Diagnostic Codes, for the code clearing procedure. 3–5. BEGINNING THE TROUBLESHOOTING PROCESS NOTE:
Whenever a transmission is overhauled, exchanged, or has undergone internal repairs, the Electronic Control Unit (ECU) must be “RESET TO UNADAPTED SHIFTS.” See Service Information Letter 16-WT-96, Revision A for further details. 1. Begin troubleshooting by checking the transmission fluid level and ECU input voltage. Remember that some problems may be temperature related. Do troubleshooting at the temperature level where the problem occurs. Check diagnostic codes by: • Using the shift selector display. (See Paragraph 6–2 for code reading.) • Using the ATDTTM or Pro-Link® 9000 diagnostic tool. 2.
When a problem exists but a diagnostic code is not indicated, refer to the Performance Complaint Section (Section 8) for a listing of various electrical and hydraulic problems, their causes, and remedies. 3. If a diagnostic code is found in the ECU memory, record all available code information and clear the active indicator (refer to Section 6). 4. Test drive the vehicle to confirm a diagnostic code or performance complaint. • If the code reappears, refer to the Diagnostic Code section (Section 6) and the appropriate code chart. The Diagnostic Code section lists diagnostic codes and their description. Locate the appropriate troubleshooting chart and follow the instructions.