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P0118 (3) Chevrolet Uplander I

Testing & Diagnostics ~226 words
  1. With the ignition ON, engine OFF, disconnect the ECT sensor and measure for 4.8-5.2 volts from the signal circuit of the ECT sensor to a good ground with a DMM. If over 5.2 volts, test the ECT signal circuit for a short to voltage, an intermittent and a poor connection at the control module. If all test OK, replace the control module. If under 4.8 volts, test the signal circuit of the ECT sensor for high resistance, an open or a short to any 5-volt reference circuit.
  2. With the ignition ON, engine OFF
  3. Connect a 3-amp jumper wire between the signal circuit of the ECT sensor and the low reference circuit.
  4. Observe the ECT parameter with a scan tool for 139°C (282°F). If more then specified value, test the ECT signal circuit for a short to any 5-volt reference circuit or a faulty connection at control module. If circuits test OK, replace the ECT sensor.
  5. Connect a 3-amp jumper wire between the signal circuit of the ECT sensor and a good ground.
  6. Observe the ECT parameter with a scan tool for 139°C (282°F). If more than the specified value, test the ECT low reference circuit for high resistance or an open. Test for a faulty connection at the control module or a faulty control module. If the circuit tests OK, replace the control module.

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