Temp sensor not working correctly on my 2004 Chevy Silverado 4.6 v8 when you start the truck it moves to 210 and drops down to 160.Also where is it located

Avalanche, Sierra, Silverado, C&K Series, 1999-2005
Coolant Temperature Sensor



Fig. Coolant temperature sensor location on...
- 1999-2005 4.8L, 5.3L, 6.0L engines
- 2000-2005 4.8L, 5.3L, 6.0L engines

The Engine Coolant Temperature (ECT) sensor resistance changes in response to engine coolant temperature. The sensor resistance decreases as the coolant temperature increases, and increases as the coolant temperature decreases. This provides a reference signal to the PCM, which indicates engine coolant temperature. The signal sent to the PCM by the ECT sensor helps the PCM to determine spark advance, EGR flow rate, air/fuel ratio, and engine temperature. The ECT is a two wire sensor, a 5-volt reference signal is sent to the sensor and the signal return is based upon the change in the measured resistance due to temperature.

How to test, follow this procedure...

1. Turn the ignition switch to ON , but do not start the engine.
2. Disconnect the sensor lead at the sensor. Connect a test lamp to the lead; The lamp should glow. If not, check the wiring, fuses and connections.
3. Disconnect the test lamp and ground the connector. The gauge should read at the HOT mark.
4. Remove the connector from ground. The gauge should read at the COLD mark.
5. At 104°F (40°C) the resistance of the sensor should be 1365 ohms.
6. At 257°F (125°C) the resistance of the sensor should be 55 ohms.

1. Remove the ECT sensor.
2. Measure and record the resistance of the ECT sensor at various temperatures, then compare those measurements to the following. The change in resistance should occur smoothly. If there are any sudden changes, the sensor is faulty.
   -4°F: 28680 ohms 14°F: 16180 ohms 32°F: 9420 ohms 50°F: 5670 ohms 68°F: 3520 ohms 86°F: 2238 ohms 104°F: 1459 ohms 122°F: 973 ohms 158°F: 467 ohms 194°F: 241 ohms 230°F: 132 ohms 266°F: 77 ohms
   
3. If the sensor tests outside of these ranges, replace the sensor.