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Home >> Subaru >> 1997 >> Legacy Outback Limited, Automatic >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> Diagnosis - 4-Speed - With 2-Digit DTCS >> Diagnostic Tests >> DTC 23: Engine Speed Signal >> 1997-98 Impreza, 1998 Forester & Legacy

1997-98 Impreza, 1998 Forester & Legacy

  1. Turn ignition switch to OFF position. Disconnect connectors from TCM and ECM. Measure resistance between TCM connector B54 and ECM B84 connector. Resistance between connector B54 terminal No. 5 and B84 connector terminal No. 64 should be 0-1 ohm. If resistance is okay, go to next step. If resistance is not within specification, repair open in harness between TCM and ECM.
  2. Measure resistance between TCM connector B54 and ground. Resistance between connector B54 terminal No. 5 and ground should be more than 100 k/ohms. If resistance is okay, go to next step. If resistance is not within specification, repair short to ground in harness between TCM and ECM.
  3. Connect connectors to TCM and ECM. With KOEO, backprobe and measure voltage between TCM B54 and connector B55s. Voltage between connector B54 terminal No. 5 and connector B55 terminal No. 10 should be more than 10.5 volts. If voltage is okay and AT OIL TEMP light illuminates, concern is intermittent and circuit has returned to normal condition. A temporary poor contact of connector or harness may be cause. Repair harness to, or connector in TCM or ECM. If resistance is not within specification, go to next step.
  4. Check for poor contact in engine speed signal circuit. If poor contact is found, repair as necessary. If contact is okay, confirm trouble code 23 by testing with new ECM. Clear all trouble codes and retest. If trouble code 23 appears again, replace TCM and retest. If trouble code 23 does not set again, ECM was cause of trouble code.
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