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Home >> Suzuki >> 2003 >> XL-7 Base, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0116: Engine Coolant Temperature Sensor Circuit - Range/Performance Problem >> 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 switch on. Using scan tool, select DATA LIST and observe ECT SENSOR parameter. Record Engine Coolant Temperature (ECT) sensor parameter. Start engine and allow it to reach normal operating temperature. With engine at idle, observe ECT SENSOR parameter on scan tool. If parameter varies more than 1.8°F between first and second temperature readings, go to step  4. If display reading does not vary more than 1.8°F between first and second temperature readings, go to next step.
  3. Check thermostat operation. Thermostat should begin to open at 175.4-182.6°F (79.7-83.7°C). Thermostat should be completely open at 203°F (95°C). Thermostat valve should lift to more than 51/64" (8 mm). If problem is found, replace thermostat as necessary. If thermostat is okay, go to next step.
  4. Turn ignition off. Disconnect ECT sensor 3-pin harness connector. ECT sensor is located at front of intake manifold. Connect a fused jumper between ECT harness connector terminal No. 1 (Orange/Black wire) and No. 3 (Gray/Yellow wire). Observe ECT SENSOR parameter on scan tool. Scan tool should read 327°F (164°C). Disconnect jumper wire from ECT sensor harness connector. Scan tool should read -40°F (-40°C). If readings are as specified, go to step  6. If readings are not as specified, repair open or short in Orange/Black or Gray/Yellow wire between ECM and ECT sensor. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If no problem with wiring is found, go to next step.
  5. Substitute a known-good ECM, and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  6. Check ECT sensor operation. Measure resistance between ECT sensor terminals while it is immersed in a container of water. Heat water slowly and ensure resistance changes as specified. See Fig 1. If ECT sensor resistance does not change as specified, replace sensor. After repair, repeat DTC CONFIRMATION TEST . If resistance is as specified, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Testing Engine Coolant Temperature Sensor Resistance
G99H51059Courtesy of SUZUKI OF AMERICA CORP.
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