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Home >> Suzuki >> 2003 >> Vitara 2D Utility, RWD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Operation >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

NOTE: For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
NOTE: Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
  1. If engine system check has been performed, go to next step. If engine system check has not been performed, perform A-4: ENGINE SYSTEM CHECK  under SYSTEM TESTS, then go to next step.
  2. Start engine and allow it to reach normal operating temperature. Let engine idle. Using scan tool, observe engine coolant temperature. If engine coolant temperature is less than 88°F (31°C), go to next step. If engine coolant temperature is more than 88°F (31°C), go to step  5 .
  3. Turn ignition switch to LOCK position. Disconnect ECT sensor 3-pin harness connector C10, located on water outlet cap, at rear of engine. See Figure . Turn ignition switch to ON position. Using scan tool, observe ECT sensor values while connecting fused jumper wire between ECT sensor harness connector C10 terminals No. 1 (Orange/Black wire) and No. 3 (Blue/White wire). See Figure . Temperature displayed on scan tool should be 327°F (164°C). If temperature value is as specified, go to next step. If temperature value is not as specified, check for open or short circuit in Orange/Black wire or Blue/White wire between ECM and ECT sensor. If open or short circuit is found, repair as necessary and DTC CONFIRMATION TEST  . If open or short circuit is not found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST  .
  4. Turn ignition switch to LOCK position. Perform ECT sensor component test. See ENGINE COOLANT TEMPERATURE SENSOR ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If ECT sensor is okay, go to next step. If ECT sensor is faulty, replace ECT sensor. See ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST  .
  5. Check thermostat operation by observing if heater takes a long time to become effective, or coolant flows into radiator on cold start. Thermostat should begin to open at 175.4-182.6°F (79.7-83.7°C). Thermostat should be completely open at 212°F (100°C). Thermostat valve should lift to more than 51/64" (8 mm) at 203°F (95°C).If thermostat is faulty, replace thermostat. After repair, repeat DTC CONFIRMATION TEST  . If thermostat is operating okay, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST  .
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