LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2002 >> Esteem GL, 4D Sedan, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 1.8L >> Diagnostic Tests >> DTC P1600: Serial Communication Problem Between ECM & TCM >> Diagnosis & Repair Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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 harness connector E92 terminal No. 31 (Green/Yellow wire). See Figure . If voltage only toggles between 4 and 5 volts, go to next step. If voltage toggles between zero and 1.5 volts and between 4 and 5 volts, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If intermittent problem is not found, go to step  5 .
  3. If voltage reading is between 4-5 volts, check for open or poor connections in Green/Yellow wire between ECM harness connector E92 terminal No. 31 and TCM harness connector E25 terminal No. 27. See Figure and Fig 1 . If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem with wiring is found, go to next step.
  4. Substitute a known good TCM, and retest system. After repair, repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete.
  5. Turn ignition off. Disconnect TCM 20-pin harness connector. TCM is located under dash, and is attached to bracket near steering column. Turn ignition on. Measure voltage between ground and TCM harness connector E26 terminal No. 27 (Green/Yellow wire). If voltage reading is 4-5 volts, go to next step. If voltage reading is not as specified, go to step  7 .
  6. Check for open in Black/White wire between IG fuse (20-amp) located in engine compartment fuse/relay block at left side of engine compartment and TCM harness connector E26 terminal No. 20. See appropriate DIAGNOSIS article in AUTOMATIC/MANUAL TRANSMISSIONS. Also, check for open in Black/Blue wire (changes to Black/Red at ground point) between ground and TCM harness connector E26 terminal No. 19. If no problem with wiring is found, replace TCM. After repair, repeat DTC CONFIRMATION TEST  .
  7. Check for short to ground in Green/Yellow wire between ECM harness connector E92 terminal No. 27 and TCM. See WIRING DIAGRAMS article. If wire is okay, turn ignition off. Disconnect ECM 34-pin harness connector E92. ECM is located under instrument panel, behind glove box. See Figure . Check for poor terminal contact at 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.
  8. Substitute a known good ECM, and retest system. After repair, 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.
scientia non olet · About LEMON Manuals