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Home >> Suzuki >> 2002 >> Esteem GL, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 1.6L >> Diagnostic Tests >> DTC P1600: Serial Communication Problem Between ECM & TCM >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. If engine system check has been performed, go to next step. If engine system check has not been performed, go to A4: ENGINE SYSTEM CHECK  under SYSTEM TESTS.
  2. Turn ignition on. Backprobing at ECM, measure voltage between ground and ECM 22-pin harness connector E92 terminal No. 5 (Green/Yellow wire). See Figure . If voltage reading is about 5 volts, go to next step. If voltage reading toggles between zero and 5 volts, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
  3. Check for open or poor terminal connections in Green/Yellow wire between ECM and TCM. See WIRING DIAGRAMS article. Also, check for an open in TCM power or ground circuits. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, go to next step.
  4. Substitute a known good TCM, and repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete. If DTC does reset, go to next step.
  5. Turn ignition off. Disconnect TCM 28-pin harness connector E25. TCM is located under dash, and is attached to bracket near steering column. Turn ignition on. Measure voltage between ground and TCM harness connector E25 terminal No. 27 (Green/Yellow wire). See Fig 1 . If reading is about 5 volts, go to next step. If voltage is not as specified, go to step  8 .
  6. Check for an open in TCM power or ground circuits. See appropriate DIAGNOSIS article in AUTOMATIC OR MANUAL TRANSMISSIONS. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, go to next step.
  7. Substitute a known good TCM, and repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete.
  8. Check for short in Green/Yellow wire between TCM and ECM. See WIRING DIAGRAMS article. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, go to next step.
  9. Turn ignition off. Disconnect ECM 22-pin harness connector E92. ECM is located under instrument panel, behind glove box. See Figure . Check for poor terminal connection in ECM harness connector E92. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, go to next step.
  10. Substitute a known good ECM, and repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete.
Fig 1: Identifying Transmission Control Module Harness Connector Terminals
G00016803Courtesy of SUZUKI OF AMERICA CORP.
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