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Home >> Buick >> 1996 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0125 - ECT Excessive Time To Reach Closed Loop >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. If other ECT related Diagnostic Trouble Codes (DTCs) are present, diagnose affected DTC(s). If no other related DTC(s) are present, go to next step.
  3. Turn ignition on, with engine off. Disconnect ECT sensor harness connector. If scan tool reads less than -31°F (-31°C), go to step 4). If scan tool reads greater than -31°F (-31°C), go to DTC P0117, ECT SENSOR CIRCUIT VOLTAGE LOW test.
  4. Using a jumper wire, jumper ECT sensor harness terminals. If scan tool indicates greater than 302°F (150°C). If scan tool indicates less than 302°F (150°C), go to DTC P0118, ECT SENSOR CIRCUIT VOLTAGE HIGH test.
  5. Reconnect ECT sensor. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and observe ECT sensor, with engine at idle. If coolant temperature reading is at least 140°F (60°C), recheck system on a cold start. See DIAGNOSTIC AIDS. If coolant temperature is not as specified, go to next step.
  6. Using DVOM, check ECT sensor resistance. See TEMPERATURE-TO-RESISTANCE VALUES table. If ECT resistance value is close as indicated, go to next step. If ECT resistance value is not as specified, go to step 8).
  7. For cooling system problem, check thermostat operation, coolant level, coolant-to-water ratio, cooling fan operation, etc. After repairs, go to step 9).
  8. Replace ECT sensor. After replacing ECT sensor, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0125. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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