Express, Savana, G1500, G2500, G3500, 1998-2005
Turn the ignition switch to
, but do not start the engine.
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.
Disconnect the test lamp and ground the connector. The gauge should read at the
Remove the connector from ground. The gauge should read at the
At 104°F (40°C) the resistance of the sensor should be 1365 ohms.
At 257°F (125°C) the resistance of the sensor should be 55 ohms.
Remove the ECT sensor.
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
If the sensor tests outside of these ranges, replace the sensor.